23 murders in Berlin - and one confessor: Maximillian Rapp has confessed to the crimes and is sentenced to life in prison. The BKA investigator Tara Schöll, however, has doubts about the guilt of the serial killer. For at least one of the acts, Rapp's alibi is watertight. Tara and her partner Henry Kloss want to convict the real murderers in the highest secrecy. Rapp surprisingly offers his help - and now tells more than he once put on the record.

Tara and Henry take on the case of the Schächter brothers who were murdered in a forest hut. Rapp, who once took responsibility for this, is working closely with them again. When Tara, Henry and Rapp return to the crime scene, Henry is attacked by a stranger.