The USS Tang was a state-of-the-art Balao class submarine, certified by the Navy to dive up to 400 feet. But in order to test her for battle, commander Dick O'Kane decides to take her even deeper.

On her third war patrol in the Pacific, the USS Sealion II, a Balao-class submarine, prepared for a daring confrontation that would make history. In the early hours of November 21, 1944 ...