Written by Ridley Pearson

One summer morning while Aidan and Sarah are visiting their grandfather,they discover a secret compartment in his battered wooden desk. Inside is a yellowed envelope that contains a piece of very thin, almost translucent, white paper, on which, handwritten in black ink, are a series of seemingly random lines; among them are what appear to be fragments of letters, but not enough to make sense. At the bottom of the page is a verse about Peter Peter and a reference to a real hotel in London. As it happens, the family is about to embark on a trip to Europe, so the children decide that while in London, they will try to locate the hotel. Through some careful sleuthing, they manage to discover its location, and once inside, they find another clue.