When a motorcyclist dies in an accident, Lieutenant Kreutzer and his younger colleague Arnold receive the order to investigate what appears to be a murder case. Head physician Dr. Nikolai, the driver of the car involved in the accident, has been behaving strangely, but he maintains his innocence and even has an alibi. In his eagerness to solve the case, Arnold sometimes jumps to rash conclusions, but Kreutzer's methodical and thorough investigation eventually leads them to the murderer.