A new, technologically-superior Soviet sub, the Red October, is heading for the U.S. coast under the command of Marko Ramius. The U.S. government thinks Ramius is planning to attack, but C.I.A. 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 Russian naval and air forces are trying to find him, too.