During a court-ordered meeting with a psychologist, schoolteacher Joanna Lindsay begins to recount her life as a troubled parent and wife via flashbacks. In one of these flashbacks, her Australian husband, Alistair, receives word that is ex-wife is preparing a custody battle over his teenage daughter Chloe. Reluctantly, Joanna decides to come with him as well as bringing their infant son Noah. While on a route flight to Australia, Joanna lashes out at a passenger when complaints of Noah’s crying get out of hand. After letting off steam, Alistair and Joanna continue their journey stopping into a shop to buy supplies. When they return to the car, Noah has mysteriously disappeared.

Joanna finds herself at the centre of a media circus as the world's press descends on Wilde Bay to report on the disappearance. She becomes obsessed with people forming theories about her child's fate on the internet, adopting a fake identity to join in the discussion. As the police investigation continues, she and Alistair are forced to adopt different strategies for coping with the constant intrusion, a pressure which threatens to break their relationship.

The police investigation begins to focus on Joanna and Alistair, as Peter gets a warrant to inspect their house and belongings. The couple look back over the day they first arrived in Australia in a desperate effort to work out what happened to their missing child, and agree to a television interview in the hope of sharing their side of the story with the world. However, as Joanna's behaviour grows increasingly unstable, a rattled Alistair goes to the police station, determined to find out what they know.

Joanna and Alistair try to rebuild their lives in the aftermath of the tragic events, but they cannot avoid drifting further and further apart. An unexpected delivery brings long-buried memories flooding back for Joanna, but the revelation calls everything they thought they knew into question as the truth about their child's disappearance finally emerges.