books
The Message in the Hollow Oak
A group of professional detectives challenge Nancy to tackle a mystery that they have failed to solve: find an invaluable message hidden by a missionary centuries ago in a hollow oak tree in Illinois. While searching the woods for the ancient tree, Nancy, Bess, and George take part in an archaeological dig investigating Indian burial mounds. All the while Nancy searches, a mysterious enemy stalks her and it becomes a race to find the message and the treasure it reveals.