Nigel searches the deserts and forests of Cretaceous Mongolia for Therizinosaurus, an obscure dinosaur with massive fossil claws, believing it to have been a huge carnivore. Throughout his journey, Marven comes face-to-face with dinosaurs such as Saurolophus, Protoceratops, Mononykus, Velociraptor and Tarbosaurus, a close relative of the famous Tyrannosaurus rex. Once Marven finds live Therizinosaurus he discovers them to have been a bizarre type of giant plant-eating theropod dinosaur.
