Nathan's not thrilled to be sharing a bedroom with his little brother, Ryan, who litters the floor with dinosaur books and replicas. Ryan even has a terrarium that he's equipped with plants like those from the time of dinosaurs, a perfect dinosaur habitat. When Nathan throws a fossil of a dinosaur egg at Ryan, it lands in the terrarium, and the two are suddenly transported to a time when dinosaurs roamed the planet. Will they survive their encounters with the dinosaurs? How will they ever make it home?