Eight-year-old Jack and his little sister, Annie, are playing in the woods during their summer holiday, when they find a mysterious tree house full of books. But these are no ordinary books and this is no ordinary tree house. Jack and Annie get more than they had bargined for when Jack opens a book about dinosaurs and wishes he could see them for real. They end up in prehistoric times with Pteranodons, Triceratops and a huge Tyrannosaurus Rex! How will they get home again? The race is on . . . !