While the ducks are running a kelp-gathering boat in the West Indies, they are told of the mystery of an armored man who appears every fifty years to kidnap a small boy. This time, the armored man kidnaps Dewey, and the ducks fight to free him from the armored man's stronghold in a grotto in a coral reef, beneath a rotten old galleon guarded by an enormous octopus.; Donald is hypnotized into believing he is a kangaroo and buys airplane tickets to Australia for himself and the nephews. In Australia the ducks try to trap Mournful Mary, the "queen of the kangaroos," and this leads to Donald's falling into the hands of savage aborigines.