School's over for the year, and it's finally summer vacation for friends Bailey, Max and Ruby Louise. They plan to swim and fish on the Chesapeake Bay every day of the summer, but when Max discovers a previously hidden cave, their plans get sidetracked. The cave walls are covered with ancient paintings of the long extinct Susquehannock Indian tribe. Hidden deeper within the cave is an unexpected treasure that is definitely not Native American. So, how did it get there and what are they going to do about it? Follow the adventure of three kids searching for an answer to the mysterious contents of the Cave of the Susquehannocks.