On the swamp world of Ichovor, one of the legendary Orkoid Brain Boys rouses from stasis.

A princess of the world-in-rebellion of Protasia steals an STC for an Imperial Battle Station. In possession of two forbidden Thinking Machines, she encodes them with the STC schematics, and launches them before the Inquisitor can capture her. It is believed she sent them to a Heretek contact in The Periphery.

On the desert world of Kalf, a young man dreams of traveling the stars. Little does he suspect he has powerful latent psyker abilities. He finds two Thinking Machines and takes them to the old Tech-Priest that lives over the ridge.

The old Mechanicus secretly recognizes both the Thinking Machines and the significance of their message. He lures the boy to come with him with tales of ancient Crusades and Ordos, of rescuing a PRINCESS from evil. Traveling to a spaceport, they convince a Rogue Trader and his xenos companion to transport them to the Penal World of Kommitzar, where they believe the Princess to be held.

Enter the Acolytes. They have to stop this conspiracy of heresy and sin before it can destroy the Imperial Battle Station being constructed to assist in the pacification of Protasia, before the Brain Boy can lure the young psyker to his swamp world for training, and before the rebellion can spread to other systems, leading to war among the stars.