Anna Maxwell Martin will guest star in a "pivotal" role in the final two episodes of Line of Duty series five

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The Bafta award-winning actor will star as Detective Chief Superintendent Patricia Carmichael, a senior anti-corruption detective brought in from outside of AC-12.

She joins the drama after the exit of this season's reigning bad guy, John Corbett (Stephen Graham), an undercover officer who was killed by the gang he had infiltrated after his cover had been blown. Things look set to come to a head soon, as Kate Fleming (Vicky McClure) and Steve Arnott (Martin Compston) are becoming increasingly suspicious that their boss, Ted Hastings (Adrian Dunbar) is a bent copper. Could she be the one to finally point the finger at Hastings?

Writer Jed Mercurio, as ever, didn't give much away, but he confirmed her role in the show would be "pivotal"... Make of that what you will.

“I’m delighted and flattered an actor of Anna Maxwell Martin’s status agreed to play this pivotal role in Line of Duty," he said. "Anna was a pleasure to work with and brought real depth to the character of DCS Carmichael.”

An newly released image from episode five shows her having what looks like a rather tense conversation with Arnott and Fleming... Check it out below.

Line of Duty continues on Sunday at 9pm on BBC1