In the late 1880's a group of passengers are rescued from their sinking ship by mysterious men in diving outfits. When they awaken they find themselves on a submarine, the Nautilus, and meet the off-putting Captain Nemo (Robert Ryan), who explains to them that he's taking them to a place of safety. They soon see that this is a domed city on the ocean floor. Among the passengers are a Senator, Robert Fraser (Chuck Connors), a woman and her son,
Barnaby and Swallow, two brothers up to no good, who are obsessed with all the gold everything is constructed of. The metal is a by-product of their oxygenation process that keeps everyone in the city alive. There's also the cowardly Lomax as high strung, claustrophobic guy who almost destroys everything in a panic when he tries to get to the surface.
When the passengers ask to leave Nemo says this is their new home. Senator Fraser takes this in stride, waiting for an opportunity to present itself-and eventually becomes allies with Nemo and his crew. The only thing that complicates this is that he falls for the local teacher, Maia (Luciana Paluzzi of THE GREEN SLIME), who has the eye of Nemo's right hand man.
There's also another danger to the city-a gigantic, hundred foot long Manta Ray that was created by the radiation released when the city was constructed. Every so often it tries to ram the place down-but Fraser manages to destroy it.
This is an interested "sequel" to 20,000 LEAGUES UNDER THE SEA. It's worth watching for the visuals alone-there are some great sets and no lame CGI!