Line of Duty

After a police convoy is ambushed, the investigation centers on DI Lindsay Denton, the sole survivor. Why did Denton allow a police convoy to proceed without backup and without firearms? Why take the route she did? How did the ambushers know? Denton quickly goes from valuable witness to prime suspect.

Following the tragedy at the hospital, AC12's Kate Fleming is planted undercover in Lindsay Denton's Missing Persons Unit.

Lindsay is denied bail and finds herself targeted in prison. Growing increasingly desperate, she tells Kate her theory of why she is being framed.

Following her attack in prison, Lindsay is allowed to visit her dying mother. Meanwhile, Dryden shrugs off allegations about possible links to the ambush.

Lindsay fights for her life as troubling details emerge of a vicious conspiracy involving corrupt police officers. Meanwhile, Hastings is under pressure.

AC12's investigation exposes a criminal gang run within the police. Steve is convinced of Lindsay's innocence, but Kate still believes she had a role in the ambush.