Alice leaves her just two-week-old daughter at home with her husband David, to go out for her first outing after giving birth. When she returns, two hours later, she insists that the baby in the crib is not hers. Despite her obvious distress, David insists that she is mistaken.
The police are called to take on the case. Detective Simon Waterhouse is sympathetic, but maintains some doubts about Alice's story. His superior, Chief Inspector Charlie Zailer, believes that Alice is suffering from some kind of delusion, due to postnatal depression. David's attitude becomes increasingly hostile and threatening, convinced that Alice is either insane or lying. What is the role of her mother-in-law in this situation? How will Alice be able to convince the police of her innocence before it's too late?