Helen Cooper has a charmed life. She's beautiful, accomplished, organised - the star parent at the school. Until she disappears.

But Helen wasn't abducted or murdered. She's chosen to walk away, abandoning her family, husband Sam, and her home.

Where has Helen gone, and why? What has driven her from her seemingly perfect life? What is she looking for? Sam is tormented by these questions, and gradually begins to lose his grip on work and his family life.

He sees Helen everywhere in the faces of strangers. He's losing control.

But then one day, it really is Helen's face he sees...