A 'tribe' of unbelievers, strange cries in the night, large footprints in the canyon, and a series of thefts have Zack and Kayla searching for answers at Thunder Mountain C.

Who is taking the horses out of the corral at night, and why? The lists of suspects is growing longer every day. Could it be one of the Mohawks, those wild cers in the cabin next to Zack's? Or could it be Mr. Morgan, the cranky old c cook whose behavior is anything but normal? What's up with all the things that have disappeared from the Cherokee cabin that Zack shares with Peter, Luke, and Max? And why does Dave, the counselor, keep telling the boys to be patient? Doesn't he understand that they have to protect themselves?

Everything is not what it seems at this summer c. Join Zack and the Cherokees-and Kayla, Zack's younger sister-as they follow the clues that lead to the startling conclusion of the Mystery at Thunder Mountain.