Line of Duty series 4: Thandie Newton to play cop under investigation in BBC series

The Westworld actor follows in the footsteps of Lennie James and Keeley Hawes

(FilmMagic)

Each new series of BBC procedural series Line of Duty focuses on a fresh anti-corruption investigation placing the spotlight on a new suspected character.

Previous characters to have clashed with AC-12 include Lennie James' DCI Tony Gates, Keeley Hawes' DI Lindsay Denton and Sgt. Danny Waldron (Daniel Mays).

The actor tasked with playing the suspect in the drama's fourth series has been named as Thandie Newton; she will play Roz Huntley, a DCI who - when episode one begins - finds herself in the middle of a career-defining case.

Speaking about her appointment, Newton - who will next be seen in HBO series Westworld - said: "I watched the last three seasons of Line of Duty with breathless admiration for its creators, both behind and in front of the camera. I couldn't be more thrilled to be joining them now."

Returning to the series are Martin Compston as DS Steve Arnott, Vicky McClure as DC Kate Fleming and Adrian Dunbar as Superintendant Ted Hastings.

Joining the cast alongside Newton are Jason Watkins, Lee Ingleby and Royce Pierrson.

Upon its debut in 2012, Line of Duty - created by Jed Mercurio - became BBC Two's most-watched original drama in ten years. The channel handed it a further two series following a critically successful second run - with another two commissioned to air on BBC One.

Filming on series 4 begins in Belfast next week with an expected air date of 2018. Mercurio is also working on Bodyguard, a new BBC series about a volatile war veteran.