Alain Marchal, wrongly accused of murdering his wife, escapes from prison the day before his execution. Before committing suicide, he contacts Monsieur Charles, a retired gangster, and asks him to investigate, find the real culprit and clear his name. Monsieur Charles accepts his request and along with his wife Ginette and two former accomplices, Paragraphe and Teddy Coffre fort, embarks on his counter-investigation.