Andy travels back 145 million years to the time of allosaurus - a massive meat-eating dinosaur that roamed the salt flats of North America. Hatty's display features a fossilised footprint of an allosaurus that she found on her travels but when the delivery of salt she needed to finish the display fails to turn up (in fact it turns out to be pepper), Andy vows to fix the problem. His mission is to travel back to the prehistoric salt flats and collect enough salt to finish the display. Along the way he befriends an allosaurus but two others turn up which are less friendly and the adventure culminates in a breathtaking chase along the salt flats as the allosauruses dodge the giant legs and long necks of a herd of diplodocus.
