Greedy sailors capture a giant lizard off the coast of Ireland and sell it to a London circus. Then its mother shows up.

Marine atomic tests cause changes in the ocean's ecosystem resulting in dangerous blobs of radiation and the resurrection of a dormant dinosaur which threatens London.

When an experimental atomic rocket crashes somewhere off-radar, its three developing scientists are joined by three Air Force men in tracking it down to a small Pacific island, where it apparently has landed on the plateau of the island's steep-walled, taboo mountain...

During the Vietnam War, a recon unit ventures to an isolated jungle valley to uncover the fate of a missing platoon. They soon find themselves in a fight for their lives against an unexpected enemy — prehistoric dinosaurs.