If you remember "Above us the Waves" (1955) you'll get the gist of this story for James Caan. He's "Bolton", a man with plenty to prove to his superiors and himself after a tragedy struck a previous command. He's a bit of a slave driver, and that doesn't make him popular amongst his crews who find themselves training more and more aboard their tiny submarines on a remote Scottish loch. A raid by some Nazi paratroopers makes them realise, though, that their operations are now on the enemy radar, so expediency kicks in and their mission announced. They are to sail to the steep-sided fjords of Nor...