Washington's Riddles

In this adventure of the Wayback book series young Mariana Jones goes back in time to 1787. The story takes place the day before the United States Constitution is to be signed. George Washington discovers that the Constitution is missing. In its place is a strange riddle. Mariana and her new friends team up to solve the riddle. Instead, the riddle leads them to two more riddles. Can they solve all of the riddles and retrieve the Constitution before time runs out?