A ferocious dinosaur awakened by an Arctic atomic test terrorizes the North Atlantic and, ultimately, New York City. End Credit quip 'Well it's been 20,000 fathoms so I recommend that you all flush your fluids and rotate your shorts!'.

Greedy American Alexander King (Fred Clark) makes an excursion to Egypt, where he hopes that archaeologist Sir Giles Dalrymple (Jack Gwillim) and young assistant John Bray (Ronald Howard) can help him unearth ancient treasures. But they eventually run into Adam Beauchamp (Terence Morgan), an accursed man with a long family history of hauntings. Adam's mere presence is enough to awaken mummy Ra-Antef (Dickie Owen), putting the entire expedition in grave danger.