The galaxy is vast, and believers in the God-Emperor revere Him in many forms. The Spiral Dawn is one of the countless sects sanctioned by the Imperial Cult. But when a group of pilgrims arrive on Redemption - the temple planet of the Imperium where the sect was born - they find themselves not in a quiet haven of enlightenment and holiness, but in a hell covered with soot clouds, where the founders of their order and the unusual Astra Militarum regiment barely get along. As tensions rise between the "peaceful" cultists and the superstitious guards, the new arrivals slowly uncover the dark secrets that lie at the heart of their religion.