In Hadley City, Sheriff Samuel Parker is getting married. He is a friend of Lucky Luke and he had the opportunity to send the Daltons to prison. When Lucky Luke learns that the Daltons have escaped and arrive by the midday train with the firm intention of revenge, the marriage is delayed and the city is plunged into anguish. Sheriff Parker decides to settle this case personally and steals Lucky Luke's revolver to replace it with a loaded gun. The arrival of the Daltons will provoke shootings and attempts to lynch but the marriage may take place. The Daltons will even appear in the wedding photo!