Dr. Robert Siedler is an experienced forensic psychologist who is asked to prepare an expert opinion for the mentally disturbed ex-alcoholic Friedhelm Knecht, who has been in custody for a long time. According to his expert assessment, he is in favor of releasing the offender, whereupon Knecht is released from prison. Shortly afterwards, however, there is a murder in which the evidence points to Knecht as the perpetrator. The suspect goes on the run and when the case causes a stir in the press, Robert is quickly found to be the scapegoat and blamed for the murder. Robert himself is shocked: has he misjudged a case for the first time? Or was his expert opinion justified and is Knecht innocent?