Aboard the Imperial Navy frigate Emathia, Brother–Librarian Nord and Brother–sergeant Kale of the Blood Angels make a startling discovery – an alien tyranid hive ship, half-destroyed and drifting through space! Under orders from the Magos Xeren, the Blood Angels board the ship to locate a lost scout team. But their fate is far from straightforward. Little do Nord and Kale realise the horrors awaiting them. For they not only risk their bodies, but their very sanity as well.