Secretive, stealthy, and utterly malignant, Genestealer Cults are the cancers growing unseen in the hidden spaces of Mankind's realm. Their purpose is to rise up and take control of Imperial worlds in the name of a xenos god. Once their brotherhood becomes strong enough, the militant throng boils by the thousand from sewers, tunnels and basements, seeping from the spires high above like insects pouring from a hidden nest.
In truth, this skulking force of monstrous xenos hybrids is in thrall to a Tyranid Hive Fleet. Unseen and utterly beyond comprehension, this inevitable force, this Great Devourer, is drawn to the prey world by the very cult that seeks to conquer it. When the doomsayers of this dark dynasty cry that the end of the world is nigh, their claims are more accurate than even they imagine.