After serving six years for killing her husband, former public prosecutor Karin Lossow is granted an early release. Against her parole officer's advice, she returns to Usedom and her old house, now known as the eponymous "murderer house".
A supermarket manageress from Ahlbeck on the island of Usedom is found dead in the neighboring Polish resort of Swinemünde. Inspector Julia Thiel and her Polish colleague Marek investigate. The dead woman was planning to meet one of her employees to discuss a mysterious property swap. The case is a challenge for Julia Thiel, because her mother of all people is a "legal adviser" to the main suspect. To cap it all, her adolescent daughter is proving difficult, having found out she's having an affair with her Polish colleague.
Sophie works in a cafe and becomes friends with Jadwiga, the girls are used to cycling together after work; one day, Jadwiga is kidnapped, and Julia, in rehabilitation after suffering an accident, sets out to find the truth about the case.
A homeless is injured in a fire on a yacht docked, Julia discovers that earlier the ship was involved in an accident where a couple was murdered but their son survived, then she wonders if he's returned to the island to avenge his parents.
Participants in an illegal car race are surprised by police and try to flee, during the escape a young man is run over and dies. Former prosecutor is driving with the son of a friend when, suddenly, a car comes directly in front of her.