New drama explores the morality of an affair.

Emily Watson (A Song For Jenny) and Ben Chaplin (Mad Dogs) are to lead the cast of BBC One’s new four-part adaptation of Louise Doughty’s best-selling psychological thriller, Apple Tree Yard.

Written by Amanda Coe (Life In Squares, Room At The Top), Apple Tree Yard tells the story of Yvonne Carmichael (Watson), married with two grown-up children she lives a contented, conventional suburban life. But her world spirals into chaos, when a chance encounter leads to an impulsive and passionate affair with a charismatic stranger, Mark Costley (Chaplin).

Despite all her careful plans to keep her home life and career safe and separate from her affair, fantasy and reality soon begin to overlap and everything she values is put at risk, as a life-changing act of violence leads to a Crown Court trial.

The Kudos produced drama also stars, Mark Bonnar (Line Of Duty), Adeel Akhtar (River), Lydia Leonard (Life In Squares), Frances Tomelty (Unforgotten) and Rhashan Stone (Strike Back).

Emily Watson says: “I am both relishing and daunted by the prospect of taking on this role; it’s grown up, steamy and of queasy moral complexity.”

Amanda Coe says: “Apple Tree Yard is that rare thing, a perfectly executed page-turner that’s also a gripping exploration of the difficult moral choices we face in adult relationships.”

Apple Tree Yard begins start filming later this month (January).