An American nuclear submarine encounters an alien species, which coincidentally causes massive electrical and hydraulic malfunctions, causing the sub to crash into an underwater cliff and sink. The navy asks the workers of a nearby underwater oil rig who are joined by a number of navy SEALS to locate and investigate the cause of the crash. As the crew embark on their mission, they encounter a number of difficulties and discover that they may not be alone. There is something else down there. Written by