Book 54 in the bestselling series, The Horus Heresy. The skies darken over Terra as the final battle for the Throne looms ever closer... As the Traitor primarchs muster to the Warmaster's banner, it is Mortarion who is sent ahead as the vanguard of the Traitor forces. But as he and his warriors make way, they become lost in the warp and stricken by a terrible plague. Once thought of as unbreakable, the legendary Death Guard are brought...