Andy travels back in time 65 million years, to the time of Tyrannosaurus rex - one of the largest meat-eating dinosaurs of its day. His mission - to climb a volcano and find a piece of pumice stone to replace the one that he accidentally broke back at the museum. Along the way he comes jaw-to-jaw with the mighty T-rex, which takes quite an interest in Hatty's backpack. But, will he succeed in time before the museum opens?