A gigantic (albeit six-armed) octopus from the greatest depths of the sea is galvanized into action when radiation from H-bomb testing in the Pacific affects its normal feeding habits. An atomic submarine captain (Kenneth Tobey) teams with a pair of scientists (Faith Domergue, Donald Curtis) to stop the monster before it terrorizes major coastal cities. But after snacking on a couple of freighters and scooping up some tasty landlubbers from a beach, the enraged sea beast manages to make its way to San Francisco, where it demolishes the Golden Gate Bridge and the Ferry Building, thwacks a helicopter out of the sky, and sweeps an enormous tentacle through Market Street, before a final showdown. Featuring stop-motion animation by special effects master Ray Harryhausen, this sci-fi adventure is a classic of the Golden Age of monster movies.