Follows Captain Alexi Vostrikov (Harrison Ford) who, at the height of the Cold War, is ordered to take over command of the nuclear missile submarine K-19, pride of the Soviet Navy. His assignment: Prepare the K-19 for sea and take her out on patrol -- no matter what the cost. But problems with the K-19 arise that may lead to a core meltdown and explosion that will certainly kill all aboard, and possibly trigger a nuclear war. Vostrikov must choose between his orders and the lives of his men.