The Riddle Book (aka Rare Book) was a rare book, because it hadn't been out in the sun too long. The cover was worn, and Alexander could only make out that it was called, "The <something> <something> Riddle Book". He browsed through it and found that a page was missing. Though he found the answer to the riddle had blown into Black Widow's web. Ali accepted the Rare Book in trade for his magic book.