As a result of an arctic nuclear test, a carnivorous dinosaur called a Rhedosaurus thaws out and starts making its way down the east coast of North America. A professor is the only witness to the beast's existence, but when he reports about it, no one believes him, not even when he identifies it as the "rhedosaurus" to a paleontologist. However, all doubts about the dinosaur disappear when the paleontologist is eaten by the Rhedosaurus during an oceanic expedition to search for the creature. The beast even approaches a lighthouse foghorn, thinking it's another of its kind. Soon thereafter, the Rhedosaurus emerges from the sea and lays waste to Manhattan Island, were it is discovered that carries a germ that causes anyone near it to become ill. Not only that, but once it is shot by the Army, its blood is revealed to be so lethal that there's the danger of a plague breaking out. This complicates the Army's job of getting rid of the Rhedosaurus, who must be killed without shedding any further blood or being burned for fear of plague. The solution to this problem soon arrives and a radioactive isotope is shot into the already existing would in the creature by a marksman. The Rhedosaurus then eventually dies.
