Zoologist and adventurer Nigel Marven travels back in time on a prehistoric safari to find some of the most spectacular animals ever to live. This time Nigel has traveled back 100 million years to Cretaceous South America, during the true time of the titans. Nigel is on the trail of the largest land animal ever to exist and manages to run into the biggest predator to ever stomp the land. Dodging giant, aggressive crocodiles, Nigel looks to capture the ultimate hunt.

Nigel searches the early Mongolia deserts and forests for Therizinosaurus, who has massive and very long claws. On his journey, Nigel dashes across a nesting ground of Protoceratops into a forest ruled by Velociraptor and then into the path of a Tarbosaurus. He also finds a Mononykus and discovers they have feathers. At a water hole he finds a pack of Velociraptor, hunting him. After he returns to the water hole (escaping the raptors using a fog horn) he sees a Therizinosaurus fend off a hungry Tarbosaurus with its formidable claws. Nigel then finds that Therizinosaurus is a herbivore that uses its sickle-claws to hook tree and bush branches towards its mouth.