In November 1984, Soviet submarine captain Marko Ramius (Sean Connery) commands Red October, a new Typhoon-class nuclear missile submarine with a stealth "caterpillar drive", rendering it undetectable to passive sonar. Ramius leaves port to conduct exercises with attack submarine V. K. Konovalov, commanded by his former student Captain Tupolev (SkarsgÃ¥rd). Once at sea, Ramius secretly kills political officer Ivan Putin (Peter Firth) and relays false orders that they are to conduct missile drills off America's east coast.The next morning, CIA analyst and ex-Marine, Jack Ryan (Alec Baldwin), after consulting with Vice Admiral James Greer (James Earl Jones), briefs United States government officials on Red October and the threat it poses. Officials in the briefing learn that the bulk of the Soviet Navy has been deployed to sink Red October and they fear Ramius plans an unauthorized nuclear strike against the United States. Ryan, however, hypothesizes that Ramius instead plans to defect, and leaves to rendezvous with the American attack submarine USS Dallas to prove his theory. Meanwhile, Tupolev, though unable to track Red October, guesses his former mentor's route and sets a course to intercept.Typhoon-class submarine, the same type as the fictional Red October.Due to the actions of an unknown saboteur, Red October's caterpillar drive fails during risky maneuvers through a narrow undersea canyon. Petty Officer Jones (Courtney B. Vance), a sonar technician aboard Dallas, has discovered a way to detect Red October using underwater acoustics, and plots an intercept course. Ryan arranges a hazardous mid-ocean rendezvous to board Dallas, where he attempts to persuade its captain, Commander Bart Mancuso (Scott Glenn), to contact Ramius and determine his intentions.The Soviet Ambassador informs the U.S. that Ramius is a renegade, and asks for help in sinking Red October. That order is sent to the U.S. Fleet, including Dallas, which has found the Soviet submarine. Ryan, however, is convinced that Ramius plans to defect with his officers and convinces Mancuso to contact Ramius and offer assistance. Ramius, stunned that the Americans correctly guessed his plan, accepts. He then stages a nuclear reactor "emergency", ordering his crew to abandon ship. After a U.S. frigate is spotted, Ramius submerges. Meanwhile, Ryan, Mancuso, and Jones come aboard via a rescue sub, at which point Ramius requests asylum in the United States for himself and his officers.Red October is suddenly attacked by Konovalov, which has tracked them across the Atlantic. As the two Soviet subs maneuver, one of Red October's cooks, Loginov (Arana), an undercover GRU agent and the secret saboteur, opens fire. He fatally wounds first officer Vasily Borodin (Sam Neill) before retreating to the nuclear missiles bay, pursued by Ryan and Ramius. Loginov shoots Ramius, wounding him, but Ryan kills Loginov before he can detonate a missile. Meanwhile, Red October makes evasive maneuvers with a diversion provided by Dallas, causing Konovalov to be destroyed by its own fired torpedo. The crew of Red October, now rescued, watch the explosion from the deck of the U.S. frigate; unaware of the second Soviet submarine, they believe that Ramius has sacrificed himself and scuttled Red October to avoid being boarded.Ryan and Ramius, their subterfuge complete, navigate Red October to the Penobscot River in Maine. Ramius admits that the reason he defected was that after he was handed the plans for Red October, a nuclear war first strike weapon, he concluded that he could never support such an action. From atop the submarine's sail deck, Ramius, pleased to have made it to America, offers Ryan a quote from Christopher Columbus. Ryan nods in agreement and offers in return, "Welcome to the New World, sir."
Output: Question: Why is there a nuclear reactor "emergency"?, Answer: So Ramius' crew can abandon ship.