Far from the eyes of a world he disdains reigns a genius inventor and the fabulous subaquatic world he has built--Captain Nemo and the Underwater City. 1850s. When a sailing ship sinks in mid-ocean, the survivors are rescued by a mysterious submarine, whose captain (Robert Ryan) ferries the survivors to the ocean floor and a fabulous underwater city enclosed by a giant, transparent dome. While some of the new guests are content to wander the city and marvel at its scientific wonders, United States Senator Robert Fraser (Chuck Conners) plots a way to escape and complete his peace-keeping mission to Europe.