When the American submarine Ulysses responds to a distress call, the Yugoslavian refugees they take onboard turn out to actually be Middle Eastern terrorists, led by Richter (Reiner Schone). They threaten to destroy Washington, D.C., using the sub's nuclear capabilities if they do not receive $100 million in gold. Former Navy SEAL James Carter (Michael Dudikoff), now a submarine designer, is brought in by Adm. Pendleton (Frederic Forrest) to sneak aboard the ship and defeat Richter.