The USS Shadow is an American nuclear submarine led by Captain Sheffield, who was recently assigned full command of the vessel. There is uncertainty on board about whether a new world war will erupt. Panicked, the Shadow's longtime executive officer, who was passed over for the command of the sub, and is convinced--unlike Sheffield--that war has begun, decides to take matters into his own hands. He mounts a full-scale mutiny and focibly confines his commanding officer to his quarters. Meanwhile the Navy has sent another sub to destroy the Shadow before its missiles are launched. With time running out and a crew loyal to his second in command, Sheffield must race against time to regain command of the Shadow, avert nuclear war and save the lives of his crew.