In World War II, the greatest threat to the British navy is the German battleship Tirpitz. While anchored in a Norwegian fjord, it is impossible to attack by conventional means, so a plan is hatched for a special commando unit to attack it, using midget submarines to plant underwater explosives.

• London Independent Producers
• John Mills
• John Gregson
• Donald Sinden
• James Robertson Justice
• Michael Medwin
• Theodore Bikel
• James Kenney
• William Russell