Harry thinks he's too old for his bucketful of dinosaurs but they think he's wrong! When a mysterious set of plastic dinosaur cards appear on his key-ring, Harry discovers he can call on an army of Back-Up Dinosaurs for some MONSTER-sized muscle! Dangerous dogs are worrying the sheep near where Harry lives. He calls on Charlie, Siri and Jack to help investigate. But it's going to take a rather special FLYING friend to save the day! Join Harry and his friends in their latest ginormous adventure...