Two teenagers, Jean and René, hide inside the Gai-Moulin nightclub in Liège with the intention of stealing money. While waiting after closing time, they discover the body of a murdered man and flee in panic. Their suspicious behavior quickly draws police attention.
Inspector Maigret investigates the case by examining the nightclub environment and questioning its staff and regulars, including a dancer. He gradually uncovers hidden tensions, lies, and relationships connected to the crime.
In the end, Maigret solves the case by carefully observing human behavior and motives rather than relying only on physical evidence. The novel emphasizes fear, guilt, and psychology more than action.