Thousands of miles away five ex-servicemen, badly wounded in Afghanistan, are preparing for a trek to the North Pole in an attempt to begin to rebuild their shattered bodies and minds. When Stone is summoned as close protection for the trek, he accepts unthinkingly, desperate for the chance to escape his own misery. But soon it is quickly clear to Stone that the coldest war of all is just beginning... Polar bears aren't the only natural born killer.