GORGO

Joe Ryan and Sam Slade are partners in a salvage business, operating the vessel Triton off the Irish coast, with Ryan as master. After a submarine volcanic eruption damages the Triton, they put in at Nara Island for repairs. At harbormaster McCartin's cottage they meet Sean, an orphan who works for McCartin, and see his collection of Viking artifacts, including a carving Sean calls "Ogra, the sea spirit."

McCartin is unwelcoming. On their way back to the ship, Ryan and Slade find the body of a drowned diver, with gold coins in his hand. They dive the harbor to investigate and catch a brief glimpse of a large creature underwater.

McCartin summons the two men and orders them to stop snooping and leave the island. Ryan counters by producing the gold coins taken from the dead diver, and threatens to report McCartin's illegal hoard to the authorities unless he cooperates.

While this confrontation occurs, a party of islanders, believing a shark killed the diver, puts out in boats with torches to hunt it. They encounter the creature, which follows them to shore. When guns fail, Joe, Sam, and the villagers drive it back into the sea with burning firebrands.

When McCarin's men threaten to leave the island the following day, Joe and Sam make a deal with McCartin, to kill the monster taking a valuable item from McCartin's hoard as payment. Sean warns them that they have made a mistake, but the two men ignore him. On the way back to the Triton Joe and Sam discuss the value of such a creature should it be captured alive.

When the crew of the Triton are successful in capturing the creature, two university scientists arrive from Dublin to meet Ryan and Slade, hoping to obtain it for scientific study. However, Ryan has already sold the creature to Dorkin's Circus in London.

Dorkin names the creature "Gorgo", after the gorgon Medusa, before transporting it to a large, enclosed pit for public exhibition in Battersea Park. Ryan and Slade meet the scientists again, who inform them the creature is an infant. With its larger mother still out there, the Royal Navy takes charge of the operation. Later that night Gorgo's mother, Ogra, emerges from the sea and attacks Nara Island in search of her offspring before leaving. When she attacks again in the morning, a Royal Navy destroyer intercepts her, but she proves immune to their weapons and sinks it, killing all aboard.

The mother later attacks London. The military intervene, but fail to stop or destroy her. Ryan and Slade split up to find Sean, with the former finding the boy and keeping him safe. Gorgo's mother is eventually reunited with her offspring and frees him from the pit before they both return safely to the sea without further incident.

Gorgo's mother attacks London, overcomes military resistance, and rescues her captive offspring before both creatures return safely to the sea.

The ending flips the usual monster movie script, focusing on the bond between mother and child rather than wanton destruction. By surviving and returning to the ocean, Gorgo and its mother reinforce the theme that nature’s forces are not easily contained—or commodified by human greed. The film closes on a note of restoration rather than annihilation.