Dr. Roth, a respected veterinarian and head of a state-owned stud farm, had accepted papers from a man for safekeeping when he was 16 years old, toward the end of the war. Years later, they are picked up. However, this act proves to be his undoing. Before he can ask others for help, he is found dead in his car. Since espionage material is found in the immediate vicinity of the car, the police hand the case over to the State Security Service, which determines that Dr. Roth was murdered. Young Thomas, whose friend and guardian was Dr. Roth, investigates on his own to clear the man who had his complete trust. In doing so, he puts his own life in danger. Thanks to a tip from stud farm employee Renate, the security officers are able to expose the murderer, uncover his connection to the West German secret service, and clear Dr. Roth.