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.

John Millsas Commandant Fraser
John Gregsonas Lieutenant Alec Duffy
Donald Sindenas Lieutenant Tom Corbett
James Robertson Justiceas Admiral Ryder
Michael Medwinas Smart
Theodore Bikelas German Officer
James Kenneyas Abercrombie
William Russellas Ramsey
O.E. Hasseas Captain of the Tirpitz
Lee Pattersonas Cox