A serpent, created by radioactivity, threatens a Spanish coastal town.

A nuclear detonation in the Atlantic re-animates a prehistoric sea monster. The creature terrorizes the Spanish coastline, attacking swimmers, boats and lighthouses without mercy. A sea captain whose ship was sunk by the monster and an American tourist whose best friend was killed by the beast team up to stop the monster, along with the help of respected oceanographer (Ray Milland).—Jeremy Lunt <[email protected]>