In 1942,the Germans are starting to play the winning front in the second world war because of an enigma code machine coming from an apparently untraceable source, which is sending out signals to Hitler's U boats as to precisely where to attack and when.
An American captain has located the source, and sends a squadron of men to take it out. However, whilst at sea, the crew locate a German warship, and after overpowering them in a gunfight, manage to take the crew of that boat as prisoners.
However, unbeknownst to them, while their attention is diverted for a brief moment, one of the prisoners lights a stick of dynamite, blowing up their boat while the American crew are rounding up information from the German boat.
The Americans find themselves trapped on a German warboat, where everything is plastered in a language none of them understand.
As enemy ships attack the sea, the crew must think and act fast if they are to come out alive.