After a flying machine snatches a railroad box car, the Challengers find it abandoned and emptied of its gold shipment. When they hear about something that plunged into the ocean, they follow below the water, but barely avoid being sunk. Ace uses a jet pack to trail the flying machine and Red hits it with carbon dioxide from his electro-suit, but the ship dives again. Prof and Rocky dive after the machine and Rocky tears it open, forcing it to surface. The Challs subdue and turn over the thugs manning the “flying amphib,” a stolen air-sea rescue craft, to the authorities.; The Challengers rush to an art gallery being robbed by Mr. Voodoo, a walking tiki mask, but he escapes. A robot spider boards their jet, accompanies them back to Challenger Mountain, photographs the mountain HQ, and returns to Mr. Voodoo, who is Multi-Man in disguise. Multi-Man creates a diagram of Challenger Mountain and follows the Challs back to their HQ, where the guys are testing a new machine. Multi-Man leads a robot army of insects against the Challs, but Prof releases a tse-tse fly and Multi-Man panics, allowing Prof to use the new machine to materialize a condor to grab Multi-Man.