The story is about an underwater oil drilling rig that is send by the US military to examine a lost submarine, which leads to an international crisis bordering on a new world war. It turns out that at the bottom of the abyss near the crash site of the submarine, an underwater city of water-dwelling aliens is located. A Navy Seal, suffering from pressure sickness, turns paranoid and tries to destroy the city with a nuclear weapon from the crashed submarine. In the original script the aliens in turn threaten to destroy all coastal regions of the world by giant tsunamis, but in the version that was ultimately shown in theatres the aliens are portrayed much more benevolently and simply rescue the main characters from the depths.

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