Despite being married to Helen Dryden, he entered into a brief relationship with then DS Lindsay Denton whilst working at Crime Audit. Denton later became pregnant with his child, but he pressured her into having an abortion and stopped seeing her, resulting in her becoming his stalker.
Dryden joined Central Police in 1983, and was trained at the Bruche Training Centre. Upon qualifying he was first posted to Hillside Lane Station in 1983. Upon being promoted to Sergeant in 1986 he was reassigned to Northby Station and later Whitecastle Station in 1987. Becoming an Inspector in 1988 he was assigned to Fayview Station and Millbarrow Station in 1989, and then Pelbury House in 1992.
Upon promotion to Chief Inspector in 1994 he returned to Northby Station in 1994, and then to the Tactical Firearms and Public Order Unit in 1996. When he became a Superintendent in 2000 he was made the Divisional Commander of of Dorden Station and later the Department Head of Haneast Station in 2001. He was later promoted to Chief Superintendent and prior to the events of Series 2 selected to be the Deputy Chief Constable of Central Police, working out of Pelbury House.
After receiving a call from DS Jayne Akers, DI Lindsay Denton contacts Dryden for approval of the extraction, as she is unable to contact her direct superior, Chief Superintendent Raymond Mallick. Dryden approves the extraction, but addresses Lindsay as "Linda".
Dryden appears at the crime scene in order to deliver a statement to the press, where he announces that PC Vincent Butler, Sgt. Alex Wallis and DS Jayne Akers have been killed in the line of duty. He also mentions how he is taking personal charge of the investigation.
Disappointed at the lack of evidence the Major Violent Crime unit has gathered with regard to the case, and the incident at South Central Hospital, Dryden demands that DCS Lester Hargreaves deliver the press conferences to save himself the embarrassment.
Ambitious and charismatic, Dryden is a politically savvy police officer.
Deputy Chief Constable Mike Dryden takes personal charge of the investigation into the ambush, assigning AC-12 to investigate Lindsay Denton and the Major Violent Crime Unit to investigate the gunmen who carried out the attack. However, AC-12 eventually come to suspect that Dryden may have his own hidden agenda for controlling the case.