Line of Duty

AC-12 investigate DCI Jo Davidson's apparent mishandling of the murder of an investigative journalist.

AC-12 suspect a cover-up as an officer on DCI Davidson's team appears to have sabotaged the inquiry into Gail Vella's murder.

On the strength of evidence from a new witness, Jo brings Terry Boyle back in for questioning. Meanwhile, Kate is torn between loyalty to Jo and wanting to assist the investigation.

DCI Jo Davidson faces increasing pressure from all sides as AC-12 make major breakthroughs in the investigation, but an attempt to interview a key witness goes horribly wrong.

AC-12 link Gail Vella’s murder with a historic case of police corruption, but forces beyond their control threaten to derail the investigation.

As AC-12 struggle to deal with the repercussions of tragic events, Hastings makes one final bid to uncover institutionalised corruption before his time runs out.

AC-12 close in on 'H', the Fourth Man (or Woman) orchestrating the network of corrupt officers.