During World War II, South Sea beachcomber Walter Eckland is persuaded to spy on planes passing over his island. He gets more than he bargained for as schoolteacher Catherine Frenau arrives on the run from the Japanese with her pupils in tow!

A spacecraft is discovered at the bottom of the Pacific Ocean, presumed to be at least 300 years old and of alien origin. A crack team of scientists and experts is assembled and taken to the ocean floor to investigate. However, the ship is not as it seems and when a giant perfect sphere is discovered in the cargo bay, things begin to fall apart.