In the Octarius Sector, the Imperium's worst fears have been realised. For years, the Tyranids of Hive Fleet Leviathan have been locked in a war of attrition with the Orks. Now, the conflict has spilt out into surrounding space, and the xenos forces descend on Imperial planets, hungry for battle and biomatter. The combined forces of the Deathwatch, numerous Space Marine Chapters, and the legions of the Adeptus Mechanicus rush to stem the tide of destruction that threatens to engulf the Pankallis Sub-sector in war. Not all hope is lost: Inquisitor Athocles Van Roth is brewing a plan – a high stakes endeavour that may result in the total defeat of the Tyranid forces. The Imperium must be ready to do whatever it takes to stop the Octarius Sector from falling to ruin. You will need a copy of the Warhammer 40,000 Core Book to use the contents of this supplement.