I read The Riddle Stone Part2. It’s the book in Oxford Reading Tree. Chip, Biff and Hong continued to solve many riddles and went on the Riddle Mountain. It is a hard work for them, but Hong could solve all riddles. Finally, they could get to the Riddle Mountain. And they were able to solve the riddle about the stange stone which Chip’2 father found.
Hunt, Roderick. (2007). The Riddle Stone Part2, England: Oxford,