The book tells the story of Petrus, the bunny born from the litter of Moon and Crystal, along with his brothers Honey, Cocoa, Nino and Nina. But Petrus was always rebellious and disobedient. Petrus did not like the rabbit life he was carrying, and he was always angry and in a bad mood. He envied the lives of other, more powerful animals, who did not have to live in dens and escape from predators. One day, his Fairy Godmother gave him a magic crystal stone. With this magic stone, Petrus can go in search of his rainbow of happiness and travel to other places and become the animals he envied. Thus, Petrus lived the experience, the life and the dramas of diverse animals, living a reality that did not know, but not finding his rainbow of happiness. Tired of successive and unsuccessful attempts, Petrus returned home. One night, something magical happened in his life, giving him proof that the true rainbow of happiness he sought so much was exactly in his den with his family.