Pero is back in Go Go Town, a fearful place in the Wild West that desperately awaits for a sheriff to come. In this town of no law and order, Pero and a boy named Jimmy try to help Annie, daughter of a saloon owner who has just been killed.

His goal is to help the weak and defenseless, but his saving a mouse makes him the most wanted in all the land. On the run from incessant, dim-witted mice, Perro befriends a young miller's boy, Pierre; together, they decide to seek fame and fortune. When they cross paths with the lovely Princess Rosa, Perro determines to get Pierre hitched to Her Royal Highness.