When Lucky Luke arrives at Painful Gulch, "city of joi and pais", he does not know that the rivalry between two families ends up weaning the inhabitants. The O-Timmins and the O-Hara have always opposed each other. They sabotage everything that can do the region good, with the aim of harming the other family. Lucky Luke is elected mayor of the city unanimously. He decides to organize a big party with contests to reconcile the two families during the ball that will close the party. Unfortunately, not everything will happen as planned. But the women will end this rivalry.