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.
How Nancy, with few clues to go on, solves this complex mystery will thrill all readers..
The young investigator pursues her dangerous adversary to an outlaws\' cave, and is threatened when she discovers an unusual treasure.
A shadowy enemy stalks Nancy and harasses everyone at the dig.
While searching the woods for the ancient tree, Nancy and her friends live with a group of young archaeologists who are excavating prehistoric Indian burial mounds on a nearby farm.
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
