As US reconnaissance overflights of Cuba resume after a hiatus following the disastrous Bay of Pigs invasion attempt, analysts are shocked to discover Russian medium-range, nuclear-tipped missiles capable of striking the East Coast. Announcing an outright blockade of Cuba would be recognized as an act of war, so President Kennedy employs the Soviet tactic of linguistic sophistry and announces a "quarantine zone." As US Navy warships move to intercept the incoming missiles, the fate of the world hangs in the balance -- and is ultimately in the hands of a single man, not in The White House or the Kremlin, but deep beneath the waves at the edge of the quarantine zone.