The galaxy is vast, and worship of the God-Emperor by His faithful takes many forms. The Spiral Dawn is one of the countless sanctioned sects of the Imperial Cult. As a gathering of Spiralytes make their holy pilgrimage to Redemption, the sect's world of origin and a shrine world of the Imperium, they find not a haven of enlightenment and introspection, but a soot-choked hellhole where their order's founders and an unorthodox regiment of Astra Militarum maintain an uneasy coexistence. As tensions between the serene congregation and the superstitious Guardsmen mount, the new arrivals begin to unravel the dark secrets concealed at the heart of their faith.