A male body is found in the Weser. For chief inspector Inga Lürsen and her colleague Stedefreund, it quickly becomes clear that the dead man is a student who met men for money. Are Lürsen and Stedefreund dealing with a serial offender? The inspectors try to reconstruct the last few days before the murder and keep coming across the name of Leon Hartwig, a young electrician who was always exactly where the victim was. Coincidence?