Strange happenings occur on a WW II submarine.

A crew, drilling offshore for oil south of Jeju island, finds a lethal alien life form instead.

A German submarine is boarded by disguised American submariners trying to capture their Enigma cipher machine.

Several months after the U.S. entry into World War II, an inexperienced U.S. Navy commander must lead an Allied convoy being stalked by a German submarine wolf pack.