A Sadistic personality disorder Latin teacher, nicknamed "Caligula" by his long-suffering students, rules his classroom at a Stockholm school like his kingdom. He is exceptionally hard on the diligent Jan-Erik, one of his students. One night Jan-Erik is returning home and finds an intoxicated young woman crying on the street. He recognizes her as Bertha, the clerk in a tobacco store near the school, and he walks her home. Bertha has a taste for men and liquor, and Jan-Erik spends most of the night on her bedside. He becomes very involved with her, and his schoolwork suffers. Bertha also has an older man whom she fears, although she will not reveal his name. It transpires that he is Caligula, and he learns of his student's involvement. He makes life harder still for Jan-Erik, and forces Bertha to do his will by threatening to suspend Jan-Erik. But Caligula is too violent with Bertha, and one day, Jan-Erik arrives to find her dead. He finds Caligula hiding in a corner, and calls the police. With no proof, however, Caligula is soon released, and quickly arranges for the expulsion of Jan-Erik, who accuses Caligula of murder, and finally strikes him in front of the principal of the school. He then goes to stay in Bertha's apartment. The principal of the school comes to the apartment, and offers his assistance in helping Jan-Erik back on track. Caligula comes to the apartment after the principal has left, seeking some sort of forgiveness, but Jan-Erik rejects him and instead walks out into the day to a view that overlooks the whole city.