A naval crew are sent forth in the second world war to retrieve a German decoder covertly which will win them the war. In order to do this the crew must disguise their own submarine as a German U-boat as to intercept another U-boat which is carrying the decoder. No radio can be used at all in fear of risking the operation. As the American crew take control of the ship, an American destroyer sinks the pseudo U-boat and the Americans are left stranded on the real German U-boat which they must use to get back home - without being sunk by the allies. The movie carries with it a high amount of suspense that is enjoyable and entertaining. The perils that the crew face underwater whilst trying to maneuver the foreign vessel are many from depth charges to torpedoes it is a typical action war movie that keeps you on the edge of your seat. The movie lacks a little variety in the script but all in all delivers a good show.