Book VIII of The Horus Heresy. News of Horus’s treachery is in the open and a time of testing has come. As Horus deploys his forces, loyalist Astartes learn that the Wordbearers are sending a fleet to Ultramar, home of the Ultramarines. Unless they can intercept and destroy it, the Ultramarines may suffer a blow from which they will never recover. Cover art by Neil Roberts.