Far north of the Arctic Circle, a nuclear bomb test, dubbed "Operation Experiment", is conducted. Prophetically, right after the blast, physicist Thomas Nesbitt (Paul Christian) muses, "What the cumulative effects of all these atomic explosions and tests will be, only time will tell." No sooner said, the explosion awakens a 30-foot (10Â m) tall, 100-foot (30Â m) long carnivorous animal known as Rhedosaurus, thawing it out of the ice where it had been held in suspended animation. Nesbitt is the only surviving witness to the beast's awakening and is later dismissed out-of-hand as being delirious at the time of his "sighting." Despite the skepticism, he persists, knowing what he saw.
The Beast begins making its way down the east coast of North America, sinking a fishing ketch off the Grand Banks, destroying another near Marquette, Canada, wrecking a lighthouse in Maine, and crushing buildings in Massachusetts. Nesbitt eventually gains allies in paleontologist Thurgood Elson (Cecil Kellaway) and his young assistant Lee Hunter (Paula Raymond) after one of the surviving fishermen identifies from a collection of drawings the very same dinosaur as Nesbitt saw. Plotting the sightings of the Beast's appearances on a map for skeptical military officers, Elson proposes the Beast is returning to the Hudson River area where fossils of Rhedosaurus were first found. In a diving bell search of the undersea Hudson River Canyon, Professor Elson is killed after his bell is swallowed by the Beast, which eventually comes ashore in Manhattan. A later newspaper report of its rampage lists "180 known dead, 1500 injured, damage estimates $300Â million".
Arriving on the scene, military troops led by Col. Jack Evans (Kenneth Tobey) first stop the Rhedosaurus with an electrified barricade, then blast a hole with a bazooka in the Beast's throat, which drives it back into the sea. Unfortunately, it bleeds all over the streets of New York, unleashing a "horrible, virulent" prehistoric contagion, which begins to infect the populace, causing even more fatalities. The infection precludes blowing up the Rhedosaurus or even setting it ablaze, lest the contagion spread further. It is then decided to shoot a radioactive isotope into the Beast's neck wound with hopes of burning it from the inside, killing it without releasing the contagion.
When the Rhedosaurus comes ashore and attacks Coney Island amusement park, military sharpshooter Corporal Stone (Lee Van Cleef) takes a rifle grenade loaded with a potent radioactive isotope and climbs on board a roller coaster. Riding the coaster to the top of the tracks, so he can get to eye-level with the Beast, he fires the isotope into its neck wound. The creature lets out a horrible howl-scream, and thrashes about, setting the park ablaze. With the park fully engulfed by the fire, the Rhedosaurus finally crashes to the ground in its death throes.
Where is the amusement park that the Rhedosaurus attacks?
Coney Island