CIA analyst Jack Ryan (ALEC BALDWIN) looks more comfortable entwined in the lives of his wife and daughter, and writing books, without the risk that would come with going out into a dangerous world, as it was at least when he was a Marine and was severely injured when his helicopter crashed, leading to his fear of flying.
But bookish as he may sound, his curiosity drives him from his home in London to the United States, summoned by his friend Admiral Greer (JAMES EARL JONES), who wants to know why a new technologically-advanced Soviet submarine is heading to the United States. Is it an act of aggression ordered by the Soviets? Is it a training exercise?
Jack is assigned to lead a briefing that includes Jeffrey Pelt (RICHARD JORDAN) the president's national security advisor and in the midst of arguments going on between higher powers, he figures it out: The submarine's commander, Captain Marko Ramius (SEAN CONNERY), is looking to defect, as it is the 23rd of October, which is the date of when his wife died. And since he has no children and therefore no further roots in the Soviet Union, he sees no reason to remain.
While the men in that briefing believe that the Soviets intend to blow up various coastal cities in the United States with their weapons systems, the national security advisor believes in Jack's theory, but only for a limited period of time before it has to be looked upon as an act of aggression. After all, with other Soviet submarines going after the Red October (which also has a silent propulsion system that enables it to glide underwater undetected), how else can it be interpreted?
So off Jack goes, unwilling at first, but without a choice, trying to track down Ramius - of whom he has some firsthand knowledge -- and find out if his intentions are indeed what Jack believes they are, having met Ramius once at a social function and writing a detailed paper on him, knowing enough about him already.