When Inspector Maigret's .45 revolver is stolen from his home, he becomes embroiled in a murder in which the gun may have played a deadly role

Maigret is the victim of a burglary in which the .45 revolver he had received as a gift from the FBI is stolen. That evening Maigret attends a dinner where François Lagrange, an acquaintance of Maigret's friend, is expected but fails to appear due to ill health. Following his instincts, Maigret decides to investigate Lagrange's absence and uncovers a body stowed in a trunk, as well as Lagrange, who refuses to talk and seems to have lost his mind. Only Maigret can uncover the truth-and the fateful role his revolver may have played.