As the epic battle for Terra rages and the future of mankind hangs in the balance, former Knight Errant Nathaniel Garro fights among the ashes and fire of the embattled Imperial Palace as the shadow of Horus Lupercal's triumph looms. From the brutal betrayal at Isstvan to the desperate flight of the Eisenstein, through his missions as Malcador the Sigillite's Agentia Primus, Garro's path has drawn him inexorably towards a destiny that can only end in bloodshed.
As he struggles to protect Euphrati Keeler, the first Saint of the Imperial Church, from the horrors of this titanic war, Garro must face his greatest enemy – his father, Mortarion, his former master, and the monstrous liege-lord of the traitorous Death Guard – in a final, shattering confrontation.