As the film commences, Captain Joe Ryan is salvaging for treasure off the coast of Ireland, when a volcano erupts, nearly sinking his ship. Ryan and his first officer, Sam Slade, take the ship to Nara Island for repairs. As they enter harbour, they discover the floating carcasses of marine animals, the first hint that something dangerous was awoken by the volcano eruption.
Ryan and Slade consult the harbor master, who also has archeological pretensions: he has been salvaging a Viking longship in the harbor. Some of his men have disappeared mysteriously; it turns out that one has died of fear. After dark, a monstrous creature surfaces, attacks a group of fishermen, then comes ashore to wreak havoc on the island. This dinosaur-like creature is supposedly 65 feet tall. The people of the island finally drive it off.
Ryan and his crew manage to capture the monster and haul it aboard their ship, tying it to the deck. Soon, university scientists arrive on Nara, hoping to collect the monster for study, but Ryan has been offered a better deal by the owner of a circus in London. When the ship arrives in London, the circus owner names it "Gorgo", after the Gorgons of Classical mythology. It is exhibited to the public in Battersea Park.
The scientists examine Gorgo, and conclude that he is not yet an adult, and that his mother must be nearly 200 feet tall. On that note of foreboding, we cut to Nara Island as Gorgo's mother ("Ogra") attacks. Ogra trashes the island, sinks a Royal Navy destroyer, and resists attack from other warships. Later, Ogra comes ashore in London, still looking for her son, and destroys Tower Bridge and Big Ben, despite being bombarded by tanks and infantry. Royal Air Force jets attack Ogra, but with no effect. Having demolished much of London, Ogra rescues Gorgo, and both mother and son return to the sea.
Behind the scenes
The film was originally set to take place in Japan; this was then changed to France, and then finally changed to the UK. According to Bill Warren's film book Keep Watching the Skies, Australia was also considered for a locale, but the producers supposedly decided that audiences "wouldn't care" if a monster attacked Australia; Australia's alleged lack of worldwide recognizable landmarks for Gorgo to destroy was also cited as a consideration.
The location where Gorgo first appears, the fictional Nara Island, is likely a tribute to the Godzilla series; Nara being a city in southern Honshu, Japan.
Scenes where Gorgo is driven through the streets of London were shot on a Sunday morning when there was no traffic. The film studio wanted Gorgo to fight the military despite director Eugène Lourié's objections. Later, Lourié would acquire a print of the film and remove the footage.
Gorgo's special effects are crude by contemporary standards, and are often mocked when the film is reviewed by modern fans. However, the film is sometimes praised for its innovative ending, which seems to have an environmentalist moral. Unusually for such films, the monsters, which are presented as innocent victims of human interference, survive and prevail.
A novelization of the film was released in paperback at the time of its original release (Gorgo by Carson Bingham (Monarch, 1960)). The film was given a comic book series, published by Charlton Comics and included work by Spider-Man co-creator Steve Ditko, from 1961 to 1965 for 23 issues. Another series, titled Return of Gorgo was published for 2 issues in 1963/64, as well as a one-shot Gorgo's Revenge in 1962.
In 1998, the film was featured on the television series Mystery Science Theater 3000 and was mocked.