The world of Herodian IV is doomed when the nightmarish tyranid hive fleets descend from the depths of space, intent on devouring every living thing there. In the vital hours before the planeet is lost, Inquisitor Kalipsia and a team of Deathwatch Spaces Marines are sent on a mission to investigate a mysterious research outpost. The terrible secret they uncover could affect the fate of all humanity, but can they escape to dafety before they are torn apart by the ravenous alien bordes?