It’s a beautiful morning in July and Nora Linde and her two children go to the beach. During the day’s first swim, Nora discovers a body in the water and the Stockholm police is notified. At first it seems to be a drowning accident but Thomas Andreasson, the detective assigned to the case, soon suspects that it is a murder case. The body is found entangled in a fishing net, and Nora figures out whose net it is so contacts Thomas. Nora wants to help the police but knows that her husband Henrik won’t approve.
The police have a suspect but Nora continues, to her husband Henrik’s annoyance, to involve herself in the police investigation. On her way to a doctor’s appointment she bumps into Thomas and provides him with information that provides new leads in the investigation.
At Henrik and Nora’s house they are preparing to celebrate Henrik’s parents’ 40th wedding. Henrik’s parents take the children to the beach but the children disappear. Whilst looking for them they make a macabre discovery that leads the case back many years. Meanwhile, feelings are developing between Nora and Thomas. Nora turns to her friend Signe for support.