An Ordo Xenos Inquisitor, suspecting an imminent Tyranid invasion of the agri-world of Avalos, has called for Deathwatch support. The Kill-Team arrives to find themselves in the middle of a battle between PDF forces and a rebel uprising stoked by a Genestealer cult. Through one night of fire and blood, they must purge the capital city of heresy and xenos taint, leaving the planet ready to face the Tyranid hordes.