Psychologist Norman Goodman (Dustin Hoffman) is astounded to be called to duty by the U. S government based on a report he wrote about dealing with extraterrestrials. Navy divers have discovered a huge and apparently alien spacecraft 1000 feet below the surface of the Pacific Ocean and Goodman’s report is being used as a template for exploring the craft. The team he recommended has been hastily pulled together and consists of mathematician Harry Adams (Samuel L. Jackson), physicist Ted Fielding (Live Schreiber), biochemist Beth Halperin (Sharon Stone), Navy Captain Harold C. Barnes (Peter Coyote), and Goodman himself. After a whirlwind training session the team takes up residence in a high tech underwater habitat so they can investigate the ship. It turns out not to be alien at all but American and inexplicably three hundred years old, sent to the bottom of the sea by an Unknown Entry Event. When a storm on the surface traps the team below for a week mysterious and deadly events begin that may be the work of an alien mind linked to a mysterious silver sphere.