Captain Nemo has built a fantastic submarine for his mission of revenge. He has traveled over 20,000 leagues in search of Charles Denver - a man who caused the death of Princess Daaker. Seeing what he had done, Denver took the daughter to his yacht and sailed away.

Society girl Rosalind Chalmers misses the last ferry to the Thousand Islands and is taken over in the decrepit motorboat of One-Cylinder Sam, who is really William Kellogg, heir to the Davidson millions trying to raise money for an expensive vase of his uncle’s that he broke. On the journey they break down and much to his surprise Rosalind, who’s hobby is engines, fixes theirs. Once landed the pair are off on a series of adventures with Rosalind mistakenly assuming “Sam” is a burglar until all is explained by which time they are in love.

A young pickpocket is taken in by an attorney who attempts to 'civilize' her.