Captain Gantt, an ego-maniacal scientist, is in a nuclear sub testing a powerful new fuel. Due to his bungling, the sub crashes into a giant web and is attacked by a monsterous sea spider. The Seaview investigates and rushes to retrieve the remaining fuel canisters before the enormous underwater pressure collapses the test sub abd detonates the fuel - an explosion which would kill millions!
Elenco: Richard Basehart , David Hedison , Robert Duvall , Terry Becker , Del Monroe , Paul Trinka , Richard Bull , Robert Dowdell .