Mysterious flare -- Factory detectives -- Ghost pilot -- Police orders -- Warehouse crash -- Aerial mission -- A strange request -- Masked attacker -- Alley escape -- Startling discoveries -- A questionable friend -- The cave clue -- The tornado -- Amazing camouflage -- Capture -- Telltale Initials -- A revealing list -- Air-chart secret -- Hideout trap -- Runway victory.

Valuable electronic parts containing platinum are being stolen from shipments made by Stanwide Mining Equipment Company's cargo planes, and Frank and Joe Hardy are called upon to assist their world-renowned detective father in solving the case.