Xena and Xander Holmes, an American brother and sister who are living in England, use clues from their ancestor Sherlock Holmes' casebook when they are asked by a classmate to find an ancient Egyptian artifact that has been missing for many years.
Hannah and her new friend Miki discover an ancient message in the stationary shop and set out to solve the mysterious riddle that could change both their lives forever.
Winston and his friends enter an all-day puzzle contest to win fifty-thousand dollars for their school, but they must also figure out who is trying to keep them from winning. Puzzles for the reader to solve are included throughout the text.