Valuable electronic parts containing platinum are being stolen from shipments made by Stanwide Mining Equipment’s cargo planes, and Frank and Joe are called upon to assist their world-renowned detective father solve the baffling case. While posing as Stanwide employees, the boys look into the truth behind the chief pilot’s death at sea. The puzzling trail of clues leads the young sleuths to an uninhabited Caribbean island, but the final,...

Frank and Joe Hardy struggle to locate two stolen paintings that contain clues to hidden treasure.

After the new hydrofoil they are guarding is stolen, the Hardy boys face frequent danger in solving a mystery involving criminals who operate by signs of the zodiac.

A chance meeting with a stranger on the road provides the Hardy brothers with a clue to a gang of local burglars.