Detective Sergeant Mack Stone's (John Hannah) wife has been missing for three months. Consumed by grief, guilt and the overwhelming desire to uncover the truth behind her disappearance, he uses every waking moment to try and find her. As he begins to lose his grip on reality, he becomes obsessed with the unsolved mystery of a man, John Dean (Anthony Head), who Stone is convinced has committed murder, staged his own disappearance, assumed a new identity, and is now feigning amnesia to cover up his own crime.

His claims against Dean seam incredible to everyone, especially to Dean's wife Jenna (Jemma Redgrave). As he works to convince her to put Dean's amnesia to the test, a string of anonymous letters arrive accusing Stone of the murder of his wife and a financial profile reveals he has been lying about his financial affairs. Stone is subsequently arrested on suspicion of murder by his partner, Ian Reid (Brendan Coyle), and his superior, DI Brennan (Patrick Malahide). Nothing will prepare you for the twists and turns of the shocking climax.