Maigret's ambitious assistant Lapointe hears a shot and a scream, coming from a villa, one evening while walking. He then sees a car racing away at high speed. The influential homeowner Richard Gendreaux, head of department stores, fights to prevent the police from entering. Maigret finally succeeds in inspecting the room where the shooting occurred. Of course, Lapointe finds no suspicious marks. Maigret nevertheless gives his young colleague the chance to solve the mystery independently... Based on the 30th Maigret novel La première enquête de Maigret (1948), published in German under the title Maigrets erste Untersuchung.