The Happy Valley star will play a social worker who is blamed for the disappearance of a black girl in Channel 4's Kiri

Sarah Lancashire will play a social worker who gets the blame for the disappearance and death of a young black girl in Channel 4’s Kiri, from the pen of Bafta-winning writer Jack Thorne.

Sarah will play Miriam, who allows Kiri to have an unsupervised visit with her biological grandparents before she moves in with her white foster family. But when Kiri disappears during the visit, the fingers of suspicion and blame from the police, the press, and even her colleagues, point firmly at Miriam.

Tobi (Lucian Msamati), Kiri’s birth grandfather, finds both his race and dysfunctional relationship with his son, the prime suspect in Kiri’s murder, put under the microscope. Meanwhile, Alice (Lia Williams), Kiri’s fiercely articulate white foster mother, watches as her family starts to crumble under the pressure of very public grief.

Beth Willis, Channel 4 Head of Drama, said: “We are so honoured and excited to have Jack [Thorne] return to Channel 4 for Kiri. Jack’s characters are uncompromising and contradictory and always utterly, recognisably human – his typical wit and warmth blast off the page right from the start. We are so thrilled to have the perfect Sarah Lancashire bringing the funny, bold and troubled Miriam to life.”

Jack Thorne, writer, said: “My mum spent most of her life in the caring professions and I’ve always wanted to find a way of examining the pressures they are put under. I’m so grateful as always for the bravery and brilliance of Channel 4 in being prepared to look these issues in the face.”

George Ormond, co-executive producer, said: “Following Miriam, Tobi and Alice as their lives are put under the spotlight is utterly compelling, an emotional roller-coaster. It’s typical of Jack’s writing that it leaves you torn – you love them, and question them at the same time. We’re delighted to have attracted such a wonderful cast, and to be working with Jack again.”

Kiri will be a four-part drama and will begin filming later in 2017 for broadcast in 2018.