An exciting new adventure for Harry and his dinosaurs - this time set in a museum! Harry has to go to the museum with Sam who is studying the Romans for a school project. Harry finds out all about his ancestors but he and the dinosaurs soon get bored of all the ancient artefacts. Before long, Harry is teaching the dinosaurs how to climb, slide on the slippy floor and play hide-and-seek - and suddenly they're lost. Mum (and even Sam) are getting worried but Nan knows exactly where to find them - in the prehistoric hall where Harry is introducing his dinosaurs to their ancestors!