Long-troubled by a catastrophic event for which he shares some of the blame, Soviet submarine Capt. Demi (Ed Harris), nevertheless, agrees to leading one final mission aboard the B-67, a vessel which is soon to be sold to the Chinese navy. Demi's compromised mental state leaves him ill-prepared to deal with the situation posed by a technician (David Duchovny) who -- acting on top-secret orders -- seizes control of the sub. His orders: Start World War III and shift the blame to the Chinese.