On a remote Caribbean island, construction workers, including the foreman, Bart Thompson, make a spectacular discovery. As they blast through the ocean's bedrock for a new harbor, they inadvertently unearth the frozen remains of a Tyrannosaurus Rex and a Brontosaurus, along with a prehistoric Neanderthal man. The icy tomb that has preserved them for millions of years is accidentally broken, exposing the bodies. When a sudden and violent tropical storm hits the island that night, the bodies are struck by lightning, leading to the unfathomable: the dinosaurs and the Neanderthal man come back to life, setting the stage for a clash between prehistory and modernity.

As the island community grapples with the real-life monsters from their nightmares, Bart Thompson and his group of local inhabitants, including the wealthy landowner’s daughter, Betty Piper, and a friendly dinosaur enthusiast, Julio, find themselves thrust into a dangerous and surreal situation. Meanwhile, the unfrozen caveman, confused and frightened, begins adapting to the new world, echoing humanity's enduring tale of survival. The presence of these creatures from a bygone era forces the islanders to band together as they confront not only the physical dangers posed by the awakened giants but also their personal fears and prejudices.