When a motorcyclist dies in an accident, lieutenant Kreutzer and his colleague Arnold receive the order to investigate the backgrounds of this mysterious case. Although the leads point to murder, head physician Dr. Nikolai, the driver of the car involved in the accident, maintains his innocence and even has an alibi. With a lot of arduous detail work, Kreutzer follows all leads and evidence. Both Nikolai’s colleagues and his son act suspiciously. Eventually, Kreutzer convicts the criminal who secretly used the physician’s car for his criminal dealings.