A German submarine hunts allied ships during the Second World War, but it soon becomes the hunted. The crew tries to survive below the surface, while stretching both the boat and themselves to their limits.

In the midst of World War II, the battle under the sea rages and the Nazis have the upper hand as the Allies are unable to crack their war codes. However, after a wrecked U-boat sends out an SOS signal, the Allies realise this is their chance to seize the 'enigma coding machine'.

After the Cold War, a breakaway Russian republic with nuclear warheads becomes a possible worldwide threat. U.S. submarine Capt. Frank Ramsey signs on a relatively green but highly recommended Lt. Cmdr. Ron Hunter to the USS Alabama, which may be the only ship able to stop a possible Armageddon. When Ramsey insists that the Alabama mus...

A World War II submarine commander finds himself stuck with a damaged sub, a con-man executive officer, and a group of army nurses.

The story of the WWII project to crack the code behind the Enigma machine, used by the Germans to encrypt messages sent to their submarines.