A 19-year-old boy, after his mother's death, starts a relationship with his father's mistress, although he is engaged. The relationship continues after the woman has become his stepmother.
In March 1792 the Swedish King Gustav III is murdered at a masked ball. Five young people are involved in the murder story, including Tintomara, a 17 year old inter-sex who dominates over the others.
A dead and unknown woman, is found in a canal. Police inspector Martin Beck becomes involved in the case. After several months the woman is identified. The police reconstruct the woman's last trip on the canal boat "Wilhelm Tham".
During his military service a man meets a woman who works in the kitchen at the camp and they start a relationship. When the man is a out on combat exercises, he becomes a witness to his Sergeant being paralyzed by a snake.