Lieutenant Hansen, commander of the old tug Island Rose, is in disgrace. Two years previously he had been instrumental in failing to warn a British cruiser that the Queen Mary, laden with three thousand Gls, was coming straight at her. The cruiser sank with the loss of eight hundred lives, leaving Hansen ostracized and ashamed. Now he has to take his battered tug right on to the British beach at Sword. His task is to mask the first landing barges of the British 'Iron Division' and prevent the first wave of infantry from being massacred. It's a do-or-die mission, but Hansen is determined to carry it out and reclaim the honour of the old tug... and his own.