The new friends find clues linking a hermit writer to a counterfeit money scheme. Setting aside other activities for the intrigue of spying, they follow the elderly man by sail to nearby Mackinac Island. To their horror, the tale turns to one of murder. A test of wills lead them through a series of terrifying obstacles to a remarkable conclusion. They soon learn that many boathouses in the Les Cheneaux Islands resort community are being looted - theirs included.
Curiosity prevails and the teens investigate.
Unknown to them, however, the escaped Mackinac murderer lurks in the shadows plotting a fiendish scheme of revenge. Illustrated by Karen Howell, Thunder Bay Press, Lansing, Michigan. Pete's idea of rest and relaxation is soon interrupted by a chance meeting with an elderly heiress. She presents Pete with a seemingly worthless poem which leads the inquisitive teens to various sites around the Island - and ultimately into the perilous grasp of a deranged treasure hunter.