When a counterterrorism raid goes tragically wrong, Detective Sergeant Steve Arnott refuses to participate in a cover-up. Ostracised by his colleagues, he transfers to an anticorruption unit, AC-12.

Having been duped into covering up Jackie’s hit and run, Gates is desperate to sever ties with her. Gates is plunged into an even more dangerous situation.

Arnott is convinced Gates played a part in Jackie’s disappearance. With Fleming’s help, the anticorruption team try to trap Gates into revealing his involvement in covering up Jackie’s crimes.

Desperate for proof of Gates’s corruption, Fleming pushes her relationship with him to the limit. But her behaviour causes Morton to question if she might not be such a loyal colleague after all.

With Gates on the run, the anticorruption team come under pressure to close the case once and for all. Arnott is forced to make some tough decisions about where his loyalties lie. Fleming and Hastings go all out to catch Gates, leading to a shattering conclusion.

A brutal ambush on a police convoy leaves three officers dead and a protected witness fighting for his life. AC-12 turns the spotlight on Lindsay Denton.