After an encounter at sea with an unknown underwater creature stalking an “atomic” submarine, Commander Matthews (Kenneth Tobey) of the US Navy works with scientists Professor Joyce (Faith Domergue) and Dr Carter (Donald Curtis) to identify it.
The creature they are dealing with is a giant, radioactive octopus (caused by American nuclear weapon testing) that has risen from the Philippine Trench in the Pacific Ocean in search of new sources of food.
As the creature attacks San Francisco, the Navy tries to trap it at the Golden Gate Bridge but it manages to enter the Bay area leading to a final confrontation with a submarine.
The humans in the cast (Columbia B players Donald Curtis, Kenneth Tobey and Faith Domergue) play second fiddle to the giant slimy stop-motion octopus – which, in fact, only actually has six legs instead of the expected eight as special effects legend Ray Harryhausen was trying to save time and money on the low budget film – as it destroys the buildings on Market Street and rips the span of the Golden Gate Bridge asunder.
The production was refused permission to film on the real Golden Gate Bridge so backgrounds of the bridge had to be filmed clandestinely from the back of a rented bread truck.
The black and white photography makes the sea beast look all the more eerie and threatening.
This film brought together producer Charles H. Schneer and Harryhausen in a professional relationship that would last until Clash of the Titans (1981), the final feature for both men.
Commander Pete Mathews
Professor Lesley Joyce
Dr John Carter
Dean Maddox Jr.
Lt. Griff, USN
Deputy Bill Nash
Richard W. Peterson