Nancy and her friends, George and Bess, are returning from a country carnival when they witness the explosion and burning of a beautiful country mansion. Fearing its occupants may be trapped in the blazing building, they rush to the rescue - and unexpectedly fund themselves confronted with a mystery that seems to be insoluble. The first clue, an anonymous diary, includes not only indecipherable handwriting, but puzzling technical drawings and chemical Buyer pays return shipping Shipping to Canada and the continental United states only