Regium stands as an eternal bulwark of the Imperium—a fortress world that has weathered countless threats across millennia. Yet its defenses now crumble under an insidious assault: parasitic plagues spread like wildfire, and its people are tormented by visions of ravenous xenos devouring them from within.

When Lieutenant Castamon of the Ultramarines recognizes the telltale marks of a Tyranid incursion, he mobilizes his strike force with lethal purpose. Racing against time, Castamon and the First Company must intercept Hive Fleet Leviathan's advance in the outer reaches before it descends upon Regium. Facing an enemy as cunning as it is savage, they will need every ounce of their legendary prowess—or watch their world consumed.

Written by Darius Hinks.