Mulligan's Western circus - his troupe, his lion and his elephant - arrive in town under the escort of Lucky Luke. Zilch, a rich businessman and organiser of the annual grand rodeo, thinks the circus is going to compete with his business and is determined to prevent it from putting on a show. Zilch even hires killer-for-hire Rattlesnake Joe - but in the end his attempts prove even more publicity for the circus.
