The novel was originally published by the U.S. Naval Institute Press—the first fictional work they ever published and still their most successful.
On 8 November 1975, the Soviet Navy frigate Storozhevoy mutinied. At the time, the Western powers believed it was an attempt to defect from Latvia to the Swedish island of Gotland. The mutiny was led by the ship's Political Officer, Captain Valery Sablin. The mutiny was unsuccessful, and Sablin was captured, court-martialed, and executed.
It is also not lost upon Ramius, whose defection is spurred by several other factors as well. In particular he is deeply affected by the death of his wife due to a doctor's incompetence. Because the doctor was the son of a Politburo member, he was above reproach. His wife's untimely death, in conjunction with a long-standing dissatisfaction with the callousness of the Soviet establishment towards its sailors and the fear of the destabilizing effect of the Red October in world affairs, ultimately exhausts Ramius' tolerance for the Soviet system's failings.
In the beginning of the novel, Ramius kills Political Officer Ivan Putin to ensure he will not interfere with the defection. In a letter to Admiral Yuri Padorin (whom Ramius refers to as Uncle Yuri), Ramius states that he is going to sail into New York Harbor. This has the same purpose and effect as Hernán Cortés' burning of his ships in the new world: it destroys the possibility of retreat and leaves no option for his men but to press on and win or die. The entire Soviet Northern Fleet (with the specific exception of missile submarines, to avoid confusion) is deployed to sink the Red October, approaching under the cover story of a search and rescue mission well within 400 km (about 250 miles) of the American coast, an excellent place to start a war of aggression if the explanations cannot be trusted.
Jack Ryan, a naval historian turned CIA analyst, deduces Ramius' plans. The U.S. high command agrees warily, while also planning for contingencies in case the Soviet Fleet has other intentions than their stated cover. As tensions rise between the U.S. and Soviet fleets, the crew of the USS Dallas, a Los Angeles class attack submarine, stumble across the secret to detecting the Red October. Ryan must contact the Red October's rebellious captain to prevent the loss of a decisive technological advantage. Through a combination of circumstances, Ryan becomes responsible for seeing the sub - and Ramius - to safety from the pursuing Soviet fleet. The U.S., in order to make the Soviets believe that the Red October has been destroyed, rescues its crew after Ramius declares a shipboard emergency; he and the officers heroically stay aboard to scuttle the submarine. Shortly thereafter, a decommissioned US ballistic missile submarine, the Ethan Allen, is blown up underwater. These two events fool the Soviets into thinking that the Red October has been lost. However, a GRU agent masquerading as a ship's cook attempts to destroy the Red October from within by firing a missile engine, hoping to incinerate the ship. During the confrontation with the agent, one of Ramius' top officers is killed, while Ramius and a British officer who boarded the vessel with Ryan are wounded. The agent is eventually killed by Ryan in the sub's missile compartment.
Meanwhile Captain Tupolev, the captain of a Soviet Alfa-class attack submarine and a former student of Ramius, while trailing what he thinks to be an Ohio-class submarine, realizes that it is the October, and pursues it. The two U.S. submarines escorting the Red October are unable to fire due to rules of engagement, and as a result the October is torpedoed but survives. After a tension-filled standoff, leading to the Red October sinking Tupolev's submarine by ramming it broadside, the Americans guide Red October safely into the eight-ten dry dock in Norfolk, VA.
The final piece of the deception involves the recovery of a pressure meter on the deep ocean floor by a US Navy deep exploration/salvage sub through sleight-of-manipulator, in the presence of a Russian military attache. This proves the wreck of the Ethan Allen is the Red October, as far as the Soviets are concerned. Now they only have to find the attack sub that disappeared at the same time...
The ultimate fate of the Red October is explained in the Clancy novel The Cardinal of the Kremlin, where it is revealed that the vessel was reverse engineered and stripped of all technology. The Red October was then sunk in a deep ocean trench to avoid discovery.
There were several differences between the novel and the film, including the Red October traveling up the Chesapeake Bay and near Tom Clancy's Calvert County home on the water and the prominence of the Royal Navy, including the HMS Invincible. The order of many events also has been changed.