On September 12, 1942, the British liner Laconia was torpedoed and sunk by German submarine U-156 commanded by Werner Hartenstein. She carried women, children, wounded soldiers, and Italian prisoners of war. Having sunk the ship, Hartenstein should have left them to their uncertain fate in the water, but instead he made the incredible decision to save as many lives as he could.

U-boat commander Werner Hartenstein has torpedoed the Laconia and then mounted an extraordinary rescue operation. U-156's deck is crowded with Allied survivors fished out of the South Atlantic. But in the fog of war, confusion reigns and U-156 is spotted by an American bomber, which moves in to attack.