Line of Duty

When DS Steve Arnott joins the anticorruption unit, he learns that the target of his first investigation is the well-respected DCI Tony Gates. Though Gates's professional conduct appears above reproach, his private life may provide his enemies the evidence they seek.

Having been duped into covering up Jackie's hit and run, Gates is desperate to sever ties with her. But as Arnott and Fleming close in on his secret, 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 behavior 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.