Davidson was born on the 22nd April 1979, in the Scottish city of Glasgow. Her mother, Samantha Davidson, told her that her father was an unknown police officer who raped her when she was 15 years old. However, it is revealed through DNA analysis, that her father was actually former Organised Crime Group senior figure Tommy Hunter, Samantha's brother and Davidson's uncle.
Prior to the events of Series 6, was assigned to the Murder Investigation Team (MIT) at Hillside Lane Station to act as Senior Investigating Officer (SIO) in Operation Lighthouse. This focused on the murder of journalist Gail Vella. Davidson was the second SIO to lead the case, taking over from DCI Billy McTulloch on October 6th 2019, nearly one month after Vella was murdered. After the arrest of DSU Ian Buckells, Davidson is promoted to Acting Detective Superintendent in his place.
Davidson is informed by Detective Sergeant (DS) Chris Lomax that intelligence from a Covert Human Intelligence Source (CHIS) has confidently identified a suspect in the murder of Gail Vella. She directs him and a team to mobilise, but first speaks with Detective Superintendent (DSU) Ian Buckells to get authorisation to deploy.
DSU Buckells authorises Direct Surveillance of the property at DCI Davidson's request. However, upon Davidson relaying that the CHIS is a male prostitute with an unclear motivation for coming forward and unknown drug history, he questions the veracity of the intelligence and halts the deployment. Davidson informs DS Lomax and Police Sergeant (PS) Farida Jatri that the operation will not be commencing that evening.
The morning after, DSU Buckells has spoken with senior Gold Command ranked officers in Central Police, who have authorised a deployment to arrest the suspect. Davidson, along with Detective Inspector (DI) Kate Fleming, DS Lomax and PS Jatri lead a convoy of police vehicles. They are accompanied by Authorised Firearms Officers from the Strategic Firearms Command based out of Hillside Lane Station, led by PS Briggs.
En route to the location, Davidson appears to notice a suspicious van parked outside of Hickey's Bookmakers, and redirects the convoy to the road behind it, much to the confusion of her colleagues. She tells DI Fleming that she believes the van looks like a getaway vehicle, and there is a possibility that the bookmakers is being robbed. The vans number plate is revealed to be false, but the rest of the team urge Davidson to simply call it in for a backup unit to deal with so they may continue to arrest the suspect in the Vella murder. Davidson refuses, stating there is a realistic possibility of a threat to the public, and gives the order for PS Briggs and his team to deploy. The two ARV's box in the van and the Authorised Firearms Officers deploy, arresting the driver and confronting four armed men as they exit the building, having indeed just robbed it. Three of the men surrender immediately to the officers, but a fourth raises his weapon and is subsequently shot.
Davidson elects to have DI Fleming remain and secure the current crime scene, whilst she and the rest of the team continue with the original objective. However, she is told via the radio that since shots have been fired, all of the Hillside Lane AFO's involved need to remain in place for forensic recovery of evidence, and a new team of armed officers will take at least an hour to mobilise.
Davidson and her team are eventually joined by a new group of AFO's from South Ferry Station, and continue on with the original deployment. Upon arriving at the location, a block of flats named Beechwood House in the Moss Heath area, she and her team take up a position and let the AFOs enter the building and prepare to enter the suspects flat. Despite being told by the watching surveillance teams that there is no sign of movement in the flat, she authorises the armed officers to force entry. Upon hearing that an occupant has been arrested, she has a coordinator from the Forensic Unit sent up to place them in a forensic suit to preserve evidence. The suspect is then brought down and placed in a police van, and is revealed to be Terry Boyle.
After Boyle is deemed mentally fit to be interviewed, Davidson begins questioning him along with DS Chris Lomax back at Hillside Lane Station. Through his lawyer Margaret Moore, he reveals his name is not "Ross Turner", and that he does not usually reside in Beechwood House but in Dorton Villas in Kingsgate. A search of the flat uncovers it has been deep cleaned, and a large appliance (most likely a fridge freezer) has been removed. She is shown to become frustrated with Boyle's lack of clarity and straight answers. However, she does present evidence that incriminates Boyle, such as a collection of photographs from Dorton Villas that suggests he was stalking Gail Vella, remote traces of strong Class A drugs and an item of his clothing containing gunshot residue traces.
Later that evening, Davidson arrives at a house in a suburban neighbourhood with a large suitcase. Upon entering, it is revealed to be the home of PS Jatri. It is shown that the two were previously in a relationship and are in the process of separating, with Davidson there to collect the last of her possessions. The two argue, with Davidson claiming she is leaving because of Jatri's paranoia and accusations of cheating. Jatri suspects Joanne is sleeping with DI Fleming, but Davidson dismisses the accusations, claiming she never cheated and would not have anyway with Fleming (who is straight). Jatri then remarks that she feels Davidson is ashamed of her and never treated her as an equal in their relationship, noting she has never even met Davidson's family. Davidson responds curtly that she "doesn't have" a family (despite having Samantha Davidson on record as her next of kin), and Jatri accuses her of lying again, however then tries to persuade Davidson to stay with her. However, Davidson leaves the house, leaving Jatri hunched over crying. Davidson briefly considers posting her set of keys through the letterbox, but decides against it.
Davidson arrives home at her apartment, and is shown have multiple high security locks and deadbolts fitted to her front door, which she secures after entering. Pouring herself a glass of wine, she paces her apartment and begins staring at a framed photograph on a chest of drawers. The photograph appears to show Davidson as a young teenager with an unnamed woman, possibly a relative. She becomes increasingly emotional whilst looking at the picture, eventually throwing the empty glass at it.
The next day, the Forensic Unit analysis of Flat 4F Beechwood House identifies another set of fingerprints, which match a known criminal named Carl Banks. Davidson notes that Boyle and Banks are of similar appearance and build, and likely could have been confused for one another by both residents at Beechwood and the police surveillance team. Banks is also known to Central Police for various violent firearms offenses and association with organised crime, making him a more likely contender to be Vella's killer. She quizzes Boyle about his association with Banks, but he remains silent.
Wanting to uncover the identity of the CHIS in order to determine whether it was Boyle or Banks who confessed to the murder, she and DI Kate Fleming confront Covert Operations Manager (COM) Detective Sergeant Marks, outside his base of operations in Administration Building 2. However, Marks refuses to identify the name of his informant, noting to Davidson that he has a legal right to remain anonymous. She appeals to DSU Buckells to overrule Marks, but is similarly rebuffed. The next day Joanne and her team respond to the site of an apparent suicide, however PS Jatri confirms that having sent an image of the deceased to Marks, he has been identified as the missing CHIS, whose name is Alastair Oldroyd.
Knowing there is not enough evidence to convince the Crown Prosecution Service to bring charges against Boyle, Davidson makes the decision to have him released without charge on monitored police bail. This infuriates DSU Ian Buckells, who is under pressure from the Chief Constable to get a breakthrough in Operation Lighthouse. Upset at Buckell's outburst, Davidson leaves the squad room and is confronted by DI Kate Fleming, who checks she is okay. Davidson remarks she is aware that the evidence is not enough to convict Boyle, and that she does not want to simply charge him as an easy scapegoat to progress the case if the real killer is still at large. Davidson briefly takes a hold of Flemings hand in an emotional way, but then walks off.
As Boyle is transported to a secure premises from Hillside Lane Station, Davidson looks on from inside.
PS Farida Jatri puts in a transfer notice citing personal reasons, as she is unable to continue working alongside Davidson in the Murder Investigation Team. When questioned by DSU Ian Buckells, Davidson does not reveal the extent of their relationship, but convinces him it would just be easier to approve the transfer so she can be another stations problem. She and DS Chris Lomax are called to a crime scene at met by DI Kate Fleming. The victim is Carl Banks, who has been dead for several days after having his throat slit. Davidson introduces the team to Jatri's replacement, PC Ryan Pilkington, who discovers the murder weapon close by to the body.
Upon hearing the news of Banks death, a team of AC-12 officers led by DI Steve Arnott enter Hillside Lane Station to investigate Operation Lighthouse and obtain copies of all documents. However, they are cut short and embarrassed when Davidson produced a signed moratorium from DCC Andrea Wise stating that no files are to be disclosed until the issue of information leakage has been resolved at the station. This includes disclosure of files to AC-12. Arnott's team reluctantly leave, and it is revealed that DI Kate Fleming tipped Davidson off that the unit was being looked into. After Superintendent Ted Hastings has a heated meeting with DCC Andrea Wise and PCC Rohan Sindwhani at Pelbury House, the moratorium is lifted and Anti Corruption Unit 12 returns to Hillside Lane Station to acquire copies of all information relating to Operation Lighthouse. DC Chloe Bishop also serves Davidson with a Regulation 15 Notice in response to her previous actions.
Davidson and Fleming go out for a meal and drinks together, and Davidson confesses she is struggling with the case, especially regarding the high profile nature of Gail Vella's murder and the fact she has had to arrest Terry Boyle, a man with learning difficulties. Later in the evening she makes thinly veiled romantic advances towards Fleming. Fleming appears to reciprocate, and asks if Davidson would like to meet up at the weekend whilst Mark Fleming has custody of her son Josh. The next morning, Davidson leaves the Croxford Street Residence and spots Jatri stalking her in plainclothes from across the street.
Davidson attends the AC-12 Building for interview accompanied by her Police Federation Representative DCI John Rix. She is questioned about her actions en route to Beechwood House that led to the last minute decision to re-route the convoy and intervene in an armed robbery taking place in Hickey's Bookmakers. Despite pressure from DI Steve Arnott and Superintendent Ted Hastings, she remains firm in asserting that it was "policing instinct" and nothing more that caused her to redirect the convoy, not any ulterior motive. When questioned about the age and low level criminal history of the perpetrators (Kevin Farmount, Jake Kilorgan, Peter Broomfield, Daniel Peronell and Dylan Ventridge) she maintains they appeared to be amateurs trying to conduct a robbery in an amateurish fashion. When pressed about the failures of maintaining surveillance on Beechwood House, and the decision to only order Directed and not Intrusive Surveillance, Davidson reveals it was due to an administrative error from a senior officer, but refuses to name DSU Ian Buckells by name.
Questioning moves on the suspicious death of Carl Banks and Alastair Oldroyd, the CHIS who reported Banks bragging about the murder of Gail Vella. Davidson puts forward her theory that Oldroyd killed Banks and then committed suicide, and argues that the timeframe and rate of decomposition of Bank's body backs this theory. Superintendent Ted Hastings disagrees, and argues she has failed to consider a the more likely theory that Banks was hired to kill Vella by the Organised Crime Group, was then killed by them himself for his silence after he started bragging, and then Oldroyd was framed for his murder and killed also to tie up all loose ends. Hastings also notes that due to the considerable size difference between Banks and Oldroyd it would be unlikely Oldroyd could have forced his way into Beechwood House, overpowered and beat Banks and replaced him with Terry Boyle. Davidson replies that such a theory is purely conjecture.
Unsatisfied with her responses to questions posed and defiance in the interview, Hastings arrests Davidson on suspicion of perverting the course of justice. However, before she is removed from interview Davidson argues that multiple other members of Operation Lighthouse (PS Farida Jatri, DS Chris Lomax and DSU Ian Buckells) as well as CHIS handler DS Marks were privy to the same information she was, and that their properties and electronics should be searched also. She is then remanded in custody at Decker Avenue Station. During a search of the property of Farida Jatri, DC Chloe Bishop and the Forensic Unit uncover a stash of unregistered burner phones. Subsequent analysis of the phones by the Cyber Crime Unit reveals the phones made calls at the exact same time the intelligence from Alastair Oldroyd was received by Operation Lighthouse. DNA on the phones also matches Jatris. Despite Jatri revealing to AC-12 that she and Davidson were in a relationship, and her belief she is being framed by Davidson, the evidence is enough for her to be arrested and charged by the Crown Prosecution Service. DI Steve Arnott notes that it looks like Jatri could have made the accusations against Davidson for reasons personal retribution, and without that evidence they do not have enough to justify keeping her under arrest.
Hastings places a call to Decker Avenue Station and has Davidson de-arrested and released from custody. She is picked up from outside the station in a marked cruiser by PC Ryan Pilkington, with whom she seems to be familiar. He asks if she is aware of what has happened with Jatri, to which Davidson responds "well, that's what happens to a rat". Davidson collects her car and drives to a deserted underpass where she pulls up alongside a van driven by a bearded man. The van drives off, revealing a box containing a burner phone identical to those found in Jatri's house. Davidson puts on a pair of forensic gloves and takes the phone, but once she gets back in her car she breaks into tears and starts to thrash around emotionally.
Davidson is informed by DS Chris Lomax that an officer from the Patrol Unit has found a witness, Deborah Devereux, who claims to have seen the argument between Alastair Oldroyd and the currently unknown man on the night that intelligence was received. Davidson and DI Kate Fleming watch Lomax interview Devereux, but are surprised when she denies that Carl Banks was the man arguing with Oldroyd after being shown an image. When Devereux says the man looked "different", she organises a PACE compliant video identification parade, in which the witness identifies Terry Boyle as the man arguing with Oldroyd.
Boyle is brought back to Hillside Lane Station for interview by Ryan Pilkington, and is questioned by Davidson and Fleming. He denies knowing Oldroyd and interacting with him in the pub that evening, insisting that "it was the other man". When Davidson tells him the witness claimed she only saw two people, Boyle becomes increasingly distressed and unable to answer questions. Despite being pushed by DI Kate Fleming, Davidson terminates the interview so Boyle can calm down. Outside she chastises Fleming for her aggressive questioning, arguing any defence lawyer could argue that the "oppressed and intimidated a vulnerable witness into incriminating himself" and thus their case could collapse.
After an apparent attempt on Boyles life (actually orchestrated by PC Ryan Pilkington) results in the death of PC Lisa Patel, Davidson and the Murder Investigation Team arrive at Edge Park Reservoir in the aftermath. Davidson remarks that it was a miracle that DI Kate Fleming just happened to be passing by, but she seems somewhat suspicious as Fleming asks to examine the patrol car that crashed into the water. The following day, she observed Fleming conduct an informal interview with Pilkington regarding the circumstances of the accident, in which he provides plausible and satisfactory answers.
Davidson is visited by DI Steve Arnott, who enquires as to why the Murder Investigation Team never pursued the possibility that Gail Vella's home was burgled after her death. She assures him he is free to ask around as her team is cooperating, however Arnott insinuates that due to the delay in AC-12 being able to properly investigate (due to Davidson conspiring with DCC Andrea Wise), she could have removed vital files before they returned. Davidson tells him that if he has any evidence backing up that allegation, to contact her Police Federation Representative and she will respond within the regulation ten working days. She also refuses to transfer custody of Terry Boyle to AC-12 for interview without a written production order. Before leaving, Arnott questions her about Farida Jatri being assaulted in HMP Brentiss and withdrawing her cooperation, and openly insinuates that only those with connections to the Organised Crime Group can get to and silence witnesses within prisons. He then tells DC Chloe Bishop that he will order the Forensic Unit to re-examine Jatri's house, but this time looking for Davidson's DNA instead.
She and DI Kate Fleming meet again outside of the office for drinks, however Davidson is much more reserved and appears to deny that she is a lesbian, attributing it to "assumptions made when you are a single woman". Although still concerned about Terry Boyle and his culpability, she dismisses the notion that the murder of Gail Vella was connected to organised crime, believing that AC-12 are simply trying to create links where there are none. Fleming has DS Chris Lomax look into the background of Deborah Devereux, the witness who came forward and identified Terry Boyle (and not Carl Banks) as the person who argued with CHIS Alastair Oldroyd on the night they received intelligence. She discovers, and reveals to Davidson that Devereux was previously arrested and held at Kingsgate Station on suspicion of assault and ABH in 2012, however the charges were later dropped due to intervention from a CID officer. That officer was Buckells, who at the time was a Detective Inspector.
She thanks Fleming for her work, and reveals she specifically brought her on as Deputy SIO as she knew as a former AC-12 officer she would not be corrupt. Knowing that Devereux was in Buckell's debt and could have easily been instructed to falsely identify Boyle, Davidson suspects that he may be involved with the conspiracy. She tells Fleming of other incidents associated with Buckells, such as the mistake with the surveillance of Beechwood House. She also lies and says that he put pressure on DS Marks to reveal Oldroyd's identity. Satisfied they have enough evidence, the two arrest him on suspicion of perverting the course of justice and transport him to the AC-12 Building. Upon arrival, he is taken into an interview room by DI Steve Arnott and DC Eldwick, and Davidson reveals they discovered missing Operation Lighthouse files in the boot of his car.
That evening Davidson returns to her home in the Croxford Street Residence, and reluctantly opens a laptop. On the screen is an encrypted instant messaging app (identical to the one used by the Organised Crime Group to communicate with H in Series 5). Davidson types a message to the Unknown User stating "all under control now", indicating that she has framed Buckells and is herself in league with the conspiracy.
After the arrest of DSU Ian Buckells, Davidson is appointed Acting Detective Superintendent to replace him and ensure continuity within Operation Lighthouse. She informs the Murder Investigation Team that she was able to convince Chief Superintendent Khan that the actions of one "bad apple" should not result in the whole team being replaced. Davidson announces that a new line of enquiry in Gail Vella's murder is that her house was robbed immediately after she was killed, with incriminating evidence she was in possession of potentially being stolen.
Becoming suspicious of the actions of PC Ryan Pilkington, Davidson calls him into her office. She informs him that he will still be nominated for the commendation recommended by Buckells, but due to his junior rank is being transferred out of the team in lieu of an officer of Sergeant or Inspector rank. Pilkington stares at her for a few seconds, before responding with thanks for the opportunity and that he understands her reasoning. Returning to her apartment in the Croxford Street Residence, Davidson attempts to make contact with the Organised Crime Group again via the encrypted laptop, stating that she is "finished". No response is received, concerning and infuriating her even more. The next evening she is confronted by Pilkington at her front door, who sneaks behind her and holds a pistol to her head. He demands she take him inside so he can tell her why she will not be removing him from the Operation Lighthouse team.
After a police convoy transporting Jimmy Lakewell is attacked and PS Ruby Jones is killed, an intimidated Lakewell removes his cooperation from the investigation into Gail Vella's murder and its association with the Organised Crime Group. Returned to HMP Blackthorn, he is murdered for being "a rat" by fellow inmate Lee Banks in front of the now imprisoned DSU Ian Buckells. The next morning at Hillside Lane Station, Pilkington calmly confronts Davidson and informs her of Lakewell's death, stating that the cause was "being a rat", leaving her emotionally shocked.
After a further search of PS Farida Jatri's house by the Forensic Unit, traces of Davidson's DNA are found throughout the property. However, the forensic evidence reveals something more concerning. DI Steve Arnott and DC Chloe Bishop explain to Superintendent Ted Hastings that the Davidson's DNA found was run through multiple databases, one containing elimination samples from Central Police and other crime related databases. It was flagged as containing similar genetic patterns to a non-police officer male nominal, whose DNA was also logged on a police database and that AC-12 have had previous dealings with. Arnott confirms that this close DNA match means that Davidson and the nominal are blood relatives.
The nominal Davidson is related to is revealed to be Tommy Hunter, the former leader of the Organised Crime Group who was murdered in Series 2 for his silence. Her exact relation to him is never verbalised, however a note on an AC-12 case board states that the DNA analysis suggests she is "both his niece and daughter". Her next of kin, Samantha Davidson, is also explained to be deceased by DC Chloe Bishop. Superintendent Ted Hastings notes that Davidson has kept her familial links with organised crime a secret throughout her time in Central Police, and this increases the likelihood that she is a corrupt officer.
Davidson questions DI Kate Fleming as to how AC-12 came to know that the White Rock Industrial Estate was one of the locations the Murder Investigation Team was planning on raiding as part of Operation Lighthouse. Fleming openly admits she informed her former colleagues, as they are conducting a lawful enquiry into Gail Vella's murder and she is obliged to assist. This infuriates Davidson, who coldly requests that Fleming request a transfer away from Hillside Lane Station, stating she does not want to "ruin her career" otherwise. After communicating with the unknown senior figure of the Organised Crime Group, Davidson is instructed to kill DI Kate Fleming to prevent her from further uncovering the conspiracy. The next day she asks Fleming if they can meet outside of work to discuss something personal, and apologises for her previous distant behaviour. That evening, Ryan Pilkington is sent to her apartment at Croxford Street Residence, and the two get in her car. Having previously asked Kate to meet her for a social drink at Frederico's Biergarten, Ryan orders Davidson to change the location to an abandoned car park.
Fleming arrives at the new location, and is met by a shaken Davidson, who begins apologising to her. Ryan then gets out the back of Davidsons car and aims a pistol at Kate, remarking that she should "have accepted the out" when Davidson requested she transfer away from Hillside Lane Station. Revealing she knows who he is, Fleming insults Ryan and questions his ability to kill, noting he "only had the bottle when someone was half drowned" (in reference to his killing of PC Lisa Patel) and is just a "little boy". He retorts by confessing he was responsible for the death of both John Corbett and Maneet Bindra, and is not concerned about forensic contamination as the weapon is workshopped and uses untraceable custom ammunition. Fleming tells him that he has been under surveillance by AC-12 and it is the end of the line for him and Davidson, which incenses him further. Davidson is shocked to discover she has been under watch, but is not surprised stating she would have done the same in Flemings position. She tries to go back to her car, telling Ryan she has "played her part" and "shouldn't have to watch" Fleming be killed. Insistent that she was aware of the surveillance, Ryan orders her away from the car and fires a warning shot above her head. This distracts him long enough for Fleming to draw her concealed firearm (which she obtained permission from the Strategic Firearms Commander to carry due to the threat posed by Pilkington, and is also authorised to carry as a trained Authorised Firearms Officer). The two engage in a tense Mexican standoff, with each demanding the other drop their weapon, much to Davidsons horror. Two shots are fired.
It is revealed that DI Kate Fleming was able to shoot Ryan Pilkington first, killing him. Wanting to know more about Davidson's involvement, and unsure of who she can trust, instead of arresting her she takes Davidson in her vehicle to Redman Road Apartments, the residence of her friend and former colleague DI Steve Arnott. Fleming explains the two have keys to eachothers houses and cars in case of operational emergencies. Infuriated, Fleming accuses Davidson of luring her to her death, but Davidson repeatedly asserts that she is not corrupt and has no say in the plan to kill her. Taking Arnott's the two begin driving, where Fleming urges her to come clean about her involvement with the Organised Crime Group, telling her she can secure a place in witness protection in exchange for her cooperation. Davidson tearfully dismisses this idea, noting that no matter how powerful you are in the group, if you turn you will be killed. She tells Fleming that the Organised Crime Group has had control over her since she joined Central Police in 1999, and the more she did their bidding the more they had to blackmail her with. Fleming reveals AC-12 are aware that Davidson is related to Tommy Hunter. Davidson then tells Fleming to drive to a location in Kingsgate in order to prove she is not corrupt.
After driving past the former house of Gail Vella, Davidson gets Fleming to stop outside the now abandoned Kingsgate Printing Services building. However, before they can enter the two officers find themselves surrounded by Authorised Firearms Officer's with the Strategic Firearms Command. It is later revealed that Arnott's vehicle had been fitted with a tracking device on the orders of DCS Patricia Carmichael and CC Philip Osborne. Carmichael arrives, followed by DI Steve Arnott and Superintendent Ted Hastings. Arnott is able to talk Davidson and Fleming into surrendering, and the two are arrested. The next morning, Davidson is transported to the AC-12 Building where she is interviewed by Carmichael, Hastings and Arnott. She is accompanied by her solicitor and Police Federation Representative DCI John Rix.
It is revealed to her that DNA analysis show that Tommy Hunter was both her uncle and father, having raped her mother (his sister) Samantha Davidson when he was 14. It is also shown that Samantha Davidson committed suicide in 1996. This has a significant emotional impact on Davidson, who breaks her wall of silence to tell the detectives she only knew Hunter as her uncle, with her mother having told her that her father was an unnamed police officer who raped her when she was 15. She explains that the Hunter family relocated to The City in the West Midlands, but when Samantha became pregnant after being raped by her brother she was forced to relocate back to Glasgow under her mothers maiden name, where she gave birth to Joanne in 1979. Davidson and her mother were uninvolved with Hunter, who continued to grow his Organised Crime Group in England, until 1995. Upon hearing that Davidson was doing well academically, and had never been in trouble with the law, Hunter travelled to Scotland and forcefully groomed her into accompanying him back to England.
He wanted her to join Central Police to serve as a mole for his organisation (a process he has also done with Matthew Cottan), which she eventually did in 1999 after undergoing training at Melton Police College. As she had been raised in Scotland and was not known in the area, her familial connections to organised crime were never uncovered in the vetting process. Knowing that she would be unable to protect her daughter, and in despair at her returning to her uncle, Samantha Davidson committed suicide in January of 1996. Davidson goes on to reveal after Hunters arrest in Series 1 the OCG began to fracture without his leadership, with both the criminals and network of police officers Hunter had formed links with wanting him dead. Thus ultimately led to Hunters murder in Series 2, alongside DS Jayne Akers, PS Alex Wallis and PC Vincent Butler, which was orchestrated by Cottan. She confirms that a new senior figure emerged after and regained control of the Organised Crime Group, and alludes that he may have been one of Hunters police associates. When asked if this person is either former DCI Marcus Thurwell or current CC Philip Osborne, she declines to answer.
As the interview progresses, Davidson also confesses to planting burner phones in the house of, and framing PS Farida Jatri. She goes on to assert that her being assigned to replace DCI Billy McTulloch as SIO on Operation Lighthouse was not fully the work of the OCG, but due to the impatience of DSU Ian Buckells with McTulloch for not progressing fast enough and thus affecting his reputation and wanting a new SIO to take over, leaving the position open for her to be assigned. She also confesses she manipulated Buckells into ordering the incorrect surveillance on Beechwood House, orchestrated the robbery of Hickey's Bookmakers's along with the OCG to serve as a distraction, and planted the missing case files in Buckells' service vehicle. Regarding the statement of Deborah Devereux, it in insinuated her false identification of Terry Boyle was actually done by Buckells himself, as he was growing desperate to be able to charge someone in relation to Gail Vella's murder.
DCS Patricia Carmichael directs her to evidence found in the abandoned Kingsgate Printing Services building near where she and Fleming were arrested. Inside the building the Forensic Unit uncovered a lock box containing various computers belonging to Gail Vella, which were taken from her house around the time of her murder and replaced with decoys. Davidson insists she had begun to suspect the devices were being hidden in the building after the arrest of Terry Boyle, due to its close location to Boyles residence in Dorton Villas, and later found them stashed there by the Organised Crime Group. Despite insisting she was taking DI Kate Fleming to the location to show her the devices, Superintendent Ted Hastings and Carmichael note she never authorised a search of the shop as part of Operation Lighthouse to discover the stolen devices legitimately, and kept their location secret for weeks after finding them. DI Steve Arnott notes that the devices were accessed by members of the OCG to see exactly what Vella was working on, hypothesising that they blackmailed or intimidated someone at MN News to provide them with the passwords. When told that Vella was investigating police involvement with organised crime in both the Sands View case and the murder of Lawrence Christopher, Davidson denies any knowledge and appears shocked. This is not believed by Hastings, who goes on to state that because her brother/cousin Darren Hunter was actively involved in the Christopher murder. When asked is she knows who DCI Marcus Thurwell is, she refuses to answer and refuses to answer whether it is him she has been communicating with.
When the line of questioning diverts to the circumstances before her arrest and the death of PC Ryan Pilkington, Davidson asserts that Pilkington was placed on the Murder Investigation Team to intimidate her, and she was aware of his links to the Organised Crime Group. However, she refuses to admit that it was DI Kate Fleming who shot Pilkington, instead claiming she took Kate's pistol off her and shot Pilkington herself. Carmichael notes the forensic evidence and gunshot residue detected does not support this, but it is not impossible given that Davidson's prints were also found on Fleming's sidearm. Concluding the interview, Carmichael informs Davidson she has been authorised by the Crown Prosecution Service to charge her with the offenses of perverting the course of justice and misconduct in public office, and will be seeking further charges of conspiracy and anything in relation to the death of Ryan Pilkington. Davidson is remanded in custody in the Vulnerable Persons Unit in HMP Brentiss, with CCTV cameras monitoring who enters and exits her cell wing. As she is escorted to her cell, Offender Management Officers Jenny Leland and Alison Merchant (aligned with the OCG and who previously assaulted Lindsay Denton and Farida Jatri whilst in custody) make eye contact with her, but do not come closer due to the presence of the cameras.
Much to her surprise, Davidson is escorted out of her cell at HMP Brentiss by prison officers, who tell her that they have received a Production Order to transport her to Hillside Lane Station for post charge interview. She is escorted to a transport van driven by PC 3947, and accompanied by SecuritVite officers Jenny Leland and Alison Merchant. Suspicious, especially because the transfer means she is no longer under the protective surveillance in the VPU, Davidson questions the reason for the interview and asks who the requesting officer is, only to be ignored by Leland.
Meanwhile at AC-12, DC Chloe Bishop contacts Superintendent Ted Hastings to inform him about the Production Order, given that he is leading a team to HMP Brentiss to interview Davidson there. DI Kate Fleming questions the validity of the order, and upon discovering that hers and DS Chris Lomax's signatures have been forged on it as requesting officers, realises it is a forgery and intended to draw Davidson away from safety. Hastings, along with Fleming and DI Steve Arnott immediately liaise with the Strategic Firearms Command and the National Police Air Service to locate and intercept the van before it can get to Hillside Lane Station. They are successful, intercepting it close to an underpass in Moss Heath, where Leland and PC 3947 are arrested, and Davidson is removed and escorted to Decker Avenue Station. Arnott then swaps jackets and vests with the arrested PC and impersonates him as the driver, with a reluctant Merchant in the passenger seat and an armed DI Kate Fleming in the back. The vehicle is then driven on to Hillside Lane Station, where as predicted members of the Organised Crime Group attempt to hijack it, still believing Davidson to be inside. The two gunmen are subdued by Arnott and Fleming, and the remainder of operatives arrested by the Strategic Firearms Command.
At secure custody in Decker Avenue Station, Arnott and Fleming assure Davidson that she is safe, her potential kidnappers have been arrested and try again to persuade her into talking in exchange for Witness Protection. Fleming in particular tells her that all of her notes reflect that Davidson's illegal actions were done due to control and coercion of others. They note she told Fleming that she believed her father to be a corrupt police officer (although it was in fact her uncle Tommy Hunter), and believing he may be The Fourth Man still calling the shots within the Organised Crime Group urge her to give up his name. Tearfully, she admits that she had no reason to doubt the man was her father, and was made to obey and fear him by Hunter after she was brought down to The City and forced to join Central Police. She names the man as former Chief Superintendent Patrick Fairbank. Fairbank is arrested, but a search of his cell at HMP Queen's Chase uncovers no communication equipment, meaning he is not who has been communicating with Davidson. The decline in Fairbank's mental capacity also renders interviewing him difficult, with Superintendent Ted Hastings being unable to get clear answers from him regarding recognising Davidson or Hunter.
A search of the villa where the body of Marcus Thurwell was found uncovers equipment used to reroute IP addresses, although further analysis reveals the end user was actually based in the UK, and Thurwell was being used as a proxy to mask its origin. Analysis of encrypted communications received by Davidson by the Cyber Crime Unit uncover a pattern of idiosyncratic spelling errors (specifically misspelling the word definitely as "definately"), which are identical to those appearing in chat logs from communications between John Corbett and Lisa McQueen. Believing this to be the marker and means of identifying The Fourth Man, Superintendent Ted Hastings orders DC Chloe Bishop and Amanda Yao to search through all case files relating to Lawrence Christopher and Operation Lighthouse for similarities. The search uncovers handwritten police reports from both 2003 and 2019, where the same misspelling is also present. This points to The Fourth Man, and the person who has been communicating with Davidson as DSU Ian Buckells.
Further investigation into Buckell's uncovers an encrypted laptop hidden in his cell in HMP Blackthorn (likely smuggled in by corrupt SecuritVite officers), as well as further digital footprints linking him to ordering Davidson's false transfer from prison, instructing her and PC Ryan Pilkington to murder DI Kate Fleming, and orchestrating and approving the robbery of the Eastfield Police Storage Facility in Series 5. Hastings notes that Buckell's has been intelligent in masquerading his corruption as incompetence, noting that even Davidson herself failed to put together the man she thought she was manipulating was actually the one pulling her strings. Buckell's denies being any sort of mastermind or "top man", noting the only person who could claim that title was Davidson's father Tommy Hunter. He remorselessly insists he simply passed on information to the Organised Crime Group and became more useful to them as he ascended the ranks of Central Police, and they did the dirty work and planning. He is shown to have amassed a significant fortune through his corruption, hiding money and various properties through a shell company called Holte End Holdings.
The AC-12 detectives theorise that Buckells was introduced to corruption and the Organised Crime Group early on in his career in Central Police, with one of the first teams he was assigned to containing corrupt officers DCI Marcus Thurwell and Inspector Philip Osborne. They also theorise that it was Buckells (and possibly Osborne) who ordered the murder of Gail Vella, as her investigation could link them the Organised Crime Group via the botched investigation into Lawrence Christopher's murder. Given that since the death of his father Darren Hunter had become a "nobody" not worth protecting, the OCG would have no reason to murder Vella in such a high profile manner themselves.
The epilogue of the series reveals that due to her cooperation, Davidson was admitted into the Witness Protection programme, and is now living under a new name in a classified location. She is shown exiting a rural cottage in the Autumn, along with a new partner and pet dog before going on a walk in the countryside.