Something is brewing in the West. A strike is paralyzing the breweries in the Wild West, leaving the saloons dry.

The residents of Neumünchen are so desperate that they ask Lucky Luke for help. The cowboy follows the dwindling beer flow all the way to Milwaukee, where the brewery owners are planning a coup: to revive production, they intend to bring in prisoners for forced labor.

And four old acquaintances of Lucky Luke immediately volunteer.