A journey beyond the limits of endurance...In the war-torn year of 1941, a dommed U-boat puts out to sea with eerie pageantry.Storms, air attacks, paralysing fear and claustrophobia plague the crew in the hellish weeks that follow. But suddenly the boat, used to being the hunter, becomes the hunted. Immobilised in the dark, hazardous depths as destroyers circle overhead, the strain on the men reaches breaking point. And then the pressure of the deep begins to crush the boat's steel skin...