Dr. Kroll has been sentenced to an asylum for criminally insane for attempting to murder his wife. After years of therapy, his psychiatrist, Dr. Kraus is convinced that he is now mentally sane and able to live in the society again.

Elder Paul Seibach has been working as a security carrier for a supermarket for a year. One day, waiting for him at the exit, the man finds a masked thug who, after robbing him, manages to escape. Back home, Seibach shows up at the door of his neighbor, Harald Rohn, claiming to have recognized him as the perpetrator of the robbery. That same evening Derrick is called to the crime scene: Seibach's body lies on the road in front of the house and his children, Lena and Eugen, cannot explain their father's tragic death.

Werner has been released from prison. His son, now the headmaster of a popular school, refuses to deal with him.

The 75th anniversary of the founding of a choir is celebrated in a hotel. At the party we sing, drink and dance. August Bark is also particularly cheerful and, during the evening, gives life to a provocative dance with the young and charming Irene Eppler. Shortly thereafter, the girl is found killed in her hotel room: she had a basal skull fracture. Chief Inspector Derrick begins to investigate trying to reconstruct the facts based on the testimony of those present. While it's not easy to identify the killer, Derrick has an idea as to who might be the culprit.

Robert Hofer accidentally meets a man in whom he recognizes an old comrade in arms named Goldinger. The man, on the other hand, claims his name is Paddenberg. A short time later, the police found Robert Hofer's body in the Forstenrieder Wald, a forest on the outskirts of Munich. Chief Inspector Derrick investigates.

After an afternoon spent in Munich, Ellen Theiss, a young student from a provincial college, does not return to the institute. Her lifeless body is found along the path through the woods that leads from the train station to the college. The news of his death caused panic among the companions: six months earlier, in fact, another girl had been murdered in similar circumstances. During the investigation, Derrick realizes that Ellen's death is to be connected to the crime that took place some time before and he devises a plan to frame the killer.

Jakob Lohbach, husband to a rich restaurant owner, dates one of the waitresses.

Something creepy is going on in the Weidau manor. Two young people are definitely murdered a couple days apart, but there's no apparent motive.

The lawyer Rieger is contacted by telephone and forced to hand over a gun to a dangerous prisoner, a certain Günter Hausmann, so that he can easily escape. The mysterious telephone operator warns Rieger that his wife has been taken hostage and will be killed if the request is not fulfilled. The lawyer agrees but, before delivering the weapon, he empties the magazine. A few days later Derrick is informed that Hausmann killed a prison guard during his escape.

A bank robbery goes down on a peaceful Monday morning. A foolishly brave customer rips the mask off from one of the robbers, and is shot right after. Derrick recognizes the shooter from the surveillance tape.

Dr. Schenk has a problem. He must ask Derrick, who lives next door, to fetch some stuff from his home. He doesn't want to go himself because his wife's lover boy is there.

A couple arrives home on a cab. Stepping out and preparing to pay the fare, they hear three gunshots. Sales consult Alfred Naujocks lies dead on the street.

Gerhard Brosch has been defrauded in stock exchange speculation, and he has lost everything, including all property of his son and daughter.

Arnold Bothe receives a severe head trauma and dies at the hospital. However he managed to drag himself to the phone and call for help.