First-look Line of Duty image sees Terry Boyle reunite with Ryan Pilkington

Teaser shots from the BBC drama's third episode show Pilkington (Gregory Piper), a member of the OCG who trained as a police officer and recently joined Joanne Davidson's team, escorting a hand-cuffed Terry (Tommy Jessop), an OCG associate with Down's Syndrome who was arrested for the murder of journalist Gail Vella, into a police car with another officer.

However, another first-look image shows Pilkington and Boyle sat alone in the back of a police car together, where the two may by discussing OCG business away from Pilkington's cop colleagues.

Episode three will see DCI Jo Davidson bring Boyle back in for questioning after a new witness comes forward with strong evidence, while Kate Fleming finds herself torn between staying loyal to her new gaffer and assisting AC-12's investigation into her.

As long-time viewers know, Pilkington and Boyle first worked together back in series one, when a young Ryan hung out in Terry's flat and noticed his large, empty freezer, which was then used by the OCG to store Jackie Laverty's (Gina McKee) body.

In series five, we watched as Ryan visited Terry, who became the OCG's designated lookout, with Lisa McQueen (Rochenda Sandall) and Miroslav (Tomi May) to ask him about the police raid on their headquarters at Kingsgate Printing Services, located opposite Terry's flat.

Series six is currently underway, with AC-12 – now headed up by Superintendent Ted Hastings (Adrian Dunbar), unofficial Detective Inspector Steve Arnott (Martin Compston) and the new DC Chloe Bishop (Shalom Brune-Franklin) – investigating DCI Joanne Davidson (Kelly Macdonald) and her handling of journalist Gail Vella's unsolved murder.

In the season's first episode, Davidson held up the police's raid on Beechwood House – a flat associated with the OCG and an integral part of their "cuckooing" plot – after suspiciously spotting an armed robbery about to happen and later arrested Terry Boyle, who police found in the flat when they finally reached the scene.

Line of Duty continues on Sundays at 9pm on BBC One. Want more Line of Duty content? Why not read our Line of Duty recap to refresh your memory on all that has taken place before season 6, or if you’re up to date, read our Line of Duty episode 2 recap. Take a look at the rest of our Drama coverage, or check out what else is on with our TV Guide.