A new technologically-superior Soviet nuclear sub, the Red October, is heading for the U.S. coast under the command of Captain Marko Ramius. The American government thinks Ramius is planning to attack. Lone CIA analyst Jack Ryan has a different idea: he thinks Ramius is planning to defect, but he has only a few hours to find him and prove it - because the entire Russian naval and air commands are trying to find Ramius, too. The hunt is on!

When a Soviet submarine gets stuck on a sandbar off the coast of a New England island, its commander orders his second-in-command, Lieutenant Rozanov, to get them moving again before there is an international incident. Rozanov seeks assistance from the island locals, including the police chief and a vacationing television writer, while trying to allay their fears of a Communist invasion by claiming he and his crew are Norwegian sailors.