The actor examines the early Cretaceous period, an era that saw an explosion in dinosaur diversity 125 million years ago. In a vast and sandy virtual river valley, he sets off in search of the fearsome velociraptor, only to find that this dreaded dinosaur made famous in the Jurassic Park films was in reality no bigger than a turkey. Stephen is joined by expert Dr Dean Lomax to observe the remarkable behaviour of this highly intelligent predator, before heading to the US to meet the dinosaur hunter who first discovered the Utahraptor.

Stephen Fry heads 66 million years into the past to the fateful last days of the dinosaurs to see how the plant-eaters fought back against deadly predators, and witnesses how a light in the sky became an extraordinary extra-terrestrial threat that signalled the end of the dinosaur's reign on earth.