Fabien is a brave and curious alien from the planet Cosmo who is excited to have an adventure. He visits a new planet that his friend Adrien found in her travels, with dinos and cavemen with long hair and beards. "Be careful, don't land and get out," she warns. "This is a planet we don't know about." As Fabien flies over the planet, he decides he wants to land and see even more. From wandering around in a sea dino's mouth to a game of hide-and-seek with an energetic T-rex, Fabien has a great time on this strange new planet-that is, until a pair of dino birds fly away with his spaceship in their claws! Now Fabien's adventure has become a challenge to retrieve his stolen spaceship. And with the help of his new friend, Mongo, a brave cave boy who carries a bongo, he just might be able to find his spaceship and fly home.