Icy waters that froze a torpedoed sailor within minutes . frozen metal that would tear the flesh from a man's hands . screaming blizzards that whipped the sea to a white fury. This was the dreaded convoy run from Hull to Murmansk, through Arctic seas patrolled by Hitler's U-boats. Into this hell went HMS Rattlesnake , a First World War tugboat that had already been sold once for the scrapheap. What her crew did not know was that their route had already been betrayed to the Germans, and the U-boats were waiting.