Line of Duty season 5: Martin Compston teases 'scariest series yet' as balaclava man joins the cast

Line of Duty actor Martin Compston has teased series five will be the “scariest yet”.

Jed Mercurio’s gripping drama returns to the small screen on Sunday night – and AC-12 is determined to track down H.

But the trio – comprised of Superintendent Ted Hastings (Adrian Dubar), DS Kate Fleming (Vicky McClure) and DS Steve Arnott (Compston) – are about to face their toughest challenges yet as they change course from chasing dodgy coppers to going after “actual criminals”.

“Usually AC-12s remit is going after bent cops so we got to a stage where we were chasing this mythical character, H, so we change tact,” Compston told reporters.

“Before we’ve been dealing with bent cops with some forced into crime but this they’re just murderers.

“The other people were cops, not out and out bad people. But he’s just a criminal, he’s a murderer. Leader of this gang who, one of which, threw me down a flight of stairs. They are just scary people.”

The Scottish actor added that it was “definitely the scariest series yet” as the anti-corruption force find themselves chasing the gang around town, two years after their last dalliances with H and their minions.

Series five will feature two new cast members with Little Boy Blue’s Stephen Graham and Girlfriend’s Rochenda Sandall taking on John Corbett and Lisa McQueen respectively.

The police force is also getting two new faces in PC Tatleen Sohota and PS Kyle Ferringham, played by Taj Atwal and Richard Pepple.

Line Of Duty is on BBC One, Sunday at 9pm. Episodes will be available after on BBC iPlayer.