A lost earring means Andy must go on another time-travelling adventure, as he returns 160 million years into the past to hunt for a prehistoric clamshell. Plunging into the waters of an ancient ocean, Andy meets some giant swimming reptiles and helps them to escape a colossal creature called Predator X.

Andy travels back 70 million years to meet the miniature magyarosaurus, a relative of the giant sauropod dinosaurs, which grew no bigger than a pony. But when he arrives on their prehistoric island home, he has to shrink down as well to hide from a giant flying reptile as tall as a giraffe.