After the Drop Site Massacre on Isstvan V, the battered and exhausted warriors of the Iron Hands, Raven Guard and Salamanders regroup on a seemingly insignificant death world. Fending off attacks from all sorts of monstrous creatures, the mistrusting allies find hope in the form of human refugees trying to escape the escalating war and being swept away by the winds of the warp. But while the Space Marines are carving out a refuge for mortals in the jungles of Pythos, darkness is gathering around them, threatening to engulf everything...