In the summer of 1989, four bodies are found in the woods. Shortly after, Barbara Neder, the sister of high-ranking federal officer Thomas Bethge, disappears without a trace. Rookie Anne Bach is assigned to investigate both cases.

Barbara's estranged husband, Robert, becomes the prime suspect after the police learn she had blackmailed him, but Anne's hunch points to a gardener who had taken Barbara home drunk. A lead suspect in the Isefort murders is announced in the press.

Four years later, the Weesenburg police have moved on from the case with no arrests, assuming Robert was responsible but have no proof. Still suspicious of Jurgen the gardener, Anne digs into his past and discovers a troubling history.

While searching Jurgen's house, Anne and her team find handcuffs with traces of what appears to be blood and excavate a car from the ground. Jurgen goes on the run but is eventually caught. Will Anne and Thomas finally get answers?

It's now 15 years later and Thomas is retired. Still unable to shake his sister's disappearance, he revives the case with the help of Anne and his old colleague Frank. Together they make a breakthrough when they interview Jurgen's old friend Heiner.

As they continue their rogue investigation, Thomas, Anne, and Frank put the pieces together between Jurgen, the Isefort murders, and Barbara's disappearance. Will Thomas and his family finally get closure after nearly 30 years?