Harry thinks he's too old for his bucketful of dinosaurs, but they think he's wrong! He looked after them when he was little and now they want to stick by him—forever . . . 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. Just a rub with his finger calls up some MONSTER-sized muscle! Dangerous dogs are worrying 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!