When the twisted Dark Mechanicus priests of the Bloodborn descend upon Quintarn, the Ultramarines are quick to move in defence of their prized agri-world. However, it soon becomes apparent that the planet's fate will not be decided by the massed battle companies of the Space Marines, but by the actions of just one lowly sergeant - Torias Telion. A master marksman and Scout with a long history of service to the Chapter, Telion must now face the worst of the Bloodborn's technological terrors and secure the city of Idrisia from the enemy advance, if the Ultramarines are to have any hope of prevailing against an enemy whose numbers swell with every victory.