Harper Collins (US) Flat Stanley's Worldwide Adventures #2: The Great Egyptian Grave Robbery

Ancient pyramids can be flat-out dangerous! Ever since Stanley was flattened by a bulletin board, there are places he can get to that no one else can. So when Stanley receives a letter from an archaeologist, he travels by airmail to Egypt to help find an ancient treasure deep in the heart of a great pyramid. But what if even the flattest boy on earth can't wriggle out of this dark tomb?and the terrible mess he finds himself in?