In 1878, the town of Fort Weakling is "terrorized" by the notorious criminal Billy the Kid. Or, more accurately, the citizens cower in fear of the things Billy, a bullying type, could supposedly do to them. Lucky Luke arrives at Fort Weakling, surprised that the street is deserted. He is then strangely greeted by the hotel manager. He meets Billy the Kid who finds him funny and invites him to drink hot chocolate in the saloon. As a result of a 'joke' of Billy's, Luke crushes a cake on his face, who finds it funny. Josh Belly, when he learns that Luke has stood up to Billy, has him made assistant sheriff. However, the fight against the bandit is more difficult than expected. His victims are so terrified that they refuse to testify against him. Luke manages, however, to find a local citizen to testify against him - Rawson, the village grocer, from whom Billy stole red caramels. But everything goes wrong. Rawson flees the village to not have to testify. Lucky Luke catches him. The trial itself is a joke. The members of the jury refuse to withdraw to deliberate and declare Billy not guilty. He leaves the court to the applause of the judge, the witness and the jury. After these failed attempts, Lucky Luke decides to teach the people that desperados are not as bad as they pretend to be. With the help of Josh Belly, he pretends to turn into a desperado and begins to terrorize the town. A stage-coach attack and a bank attack are organized. Citizens start demonstrating for Billy the Kid to defend them against Lucky Luke. Completely taken aback, Billy proposes an alliance with Luke who rejects it with contempt. A duel is organized between the two in the main street but the support of the population for Billy completely makes him break down and Luke captures him. The citizens realized that Billy the Kid was not that bad and they finally testify at his trial. Billy is sentenced to 1247 years in prison.
Characters
Billy the Kid: Spoilt child with a turned-up nose and a freckled face; he only drinks hot chocolate and loves soft caramels. He will ultimately be sentenced to more than 1,200 years of forced labor. He will also appear as a main character in The Escort, and as a secondary character in The Black Hills, Jesse James and Belle Starr.
Josh Belly: Director of The Clairon newspaper, he dares to resist Billy and allies with Lucky Luke.
Mr. Bonney: Billy's father, who spanks him during his first diligence attack and deprives him of dessert; he adds that this deprivation will be applied to each new attack, which results in the departure of Billy.
Kirk: Billy asks him to read the paper, but as he calls for mobilization against Billy, he prefers to invent a fairy tale.
Sarah and Foster Rawson: Village grocers, suppliers of soft caramels for Billy, by whom they are terrorized.
Sam: Saloon bartender, he only serves hot chocolate.
Judge Yelloliver : He acquits Billy in his first trial, but when the latter, neutralized, appears a second time, he sentences him to 1,247 years of forced labor after nine seconds of deliberation.