This movie is about the USS Tunny (SS-282) and the procedure she helped pioneer — firing the Regulus missile. The Regulus was the world’s first nuclear cruise missile, and a stop-gap weapon that served the Navy until the arrival of the Polaris weapon system. The Gato-class USS Tunny served three years in the Pacific during WWII, and was brought back into service in 1953 to assist in the development of the Regulus missile system. The U.S. strategy at this time, was to prevent an all out nuclear attack by the Soviet Union through the concept of Mutually Assured Destruction, or MAD. Submarine-launched missiles were envisioned as a key component of this strategy, but required sophisticated technologies be developed. So, long before the solid-fueled, underwater-launched Polaris was ready to be deployed, the air-breathing, surface-launched Regulus was put into service. The USS Tunny was placed into active duty in 1957 and for 8 years made deterrent patrols off the coast of the Soviet Union. The development of Regulus missile was an amazing feat of engineering, cost control, and foresight. It was powered by a jet engine, used solid rocket boosters to assist getting it airborne off the short deck of a submarine, and could be flown and guided remotely from a submerged boat or airborne chase aircraft.