Why is a wealthy sportsman so frightened by the serpent design on a mysterious balloon that he begs Frank and Joe Hardy to protect him? And who stole the ancient life-size chess king which is to be presented to the winner of the world chess championship? Targets of diabolical enemies, Frank and Joe find a clue that leads them across the Pacific to Hong Kong to help the police smash an international criminal organization.

Their efforts to recover a stolen ancient chess piece lead the Hardy brothers to Hong Kong where they help smash an international criminal organization.