The Hunt for Red October, Tom Clancy's first novel, appeared in 1984. The story follows the intertwined adventures of Soviet submarine captain Marko Ramius, and a CIA analyst named Jack Ryan. Ramius intends to defect to the United States with his officers and the experimental missile submarine Red October which is equipped with a revolutionary stealth propulsion system making it extremely difficult to detect with regular methods. Ryan figures out what the submarine is up to, and through a combination of circumstances becomes responsible for seeing the sub to safety from the pursuing Soviet naval fleet.

The novel is sometimes referred to as the first real example of the techno-thriller, a hybrid between the spy thriller and science fiction in which attention to technical and operational detail about military and intelligence activities is paramount.

Many of the characters in the novel appear throughout Clancy's subsequent works, particularly Ryan, who is the central character of many of Clancy's novels.

The novel was made into a commercially-successful movie starring Sean Connery as Ramius and Alec Baldwin as Ryan, and featuring James Earl Jones and Sam Neill.