Dr Yvonne Carmichael's life is about to be turned upside down when she finds herself taking unexpected risks. An encounter with a charismatic stranger begins a passionate affair and Yvonne will soon be out of her depth. Who is this mysterious guy? Following a passionate moment, a shocking act of violence changes everything.
Starring Emily Watson, Ben Chaplin, Mark Bonnar
Begins Sunday 22 January on BBC One - 21:00