One of the early novels of the modern techno-thriller genre, the book tracks the efforts of a disgruntled Soviet submarine captain to defect, with his Typhoon-class nuclear ballistic missile submarine "Red October," to the United States. Aside from the ICBM she carries, the ship has a new propulsion system that sounds like normal underwater seismic noise, essentially impossible to detect using normal submarine sonar systems optimized for mechanical noises and transient sounds. Jack Ryan, Clancy's hero, here performing as a CIA systems analyst, begins pulling the thread on the "Red October" when he is assigned to analyze a photograph of the ship under construction in it's dry dock that exhibits an unusual shape built into the hull. The pace and action continue to build through the book to a surprising climax.