The Librarian flexed his fingers, and his force axe hummed a song of death in his hand.

"It was in the time of Commander Aradiel, a hundred summers gone," said Bloody Moon. "We were aboard the battlebarge Angelus Morte on sector edge patrol when the alarms went off. Sensor probes indicated that a space hulk had dropped from warp space near us. Deep scanning revealed nothing. We were ordered to investigate.

"We crouched within the boarding torpedoes and were fired at the hulk. It was unpowered and dark when we disembarked, so helmet lights on, we moved to secure the perimeter. We met no resistance, but as per standard operational procedures, we proceeded with extreme caution.

"We identified the hulk as Prison of Lost Souls, an appropriate name as it turned out. We moved nervously through the shadowy corridors, for the taint of the warp still hung about the craft. It made us uneasy."

"At first, there was no sign of danger. Then we came across the bodies of some Space Wolves. They had been riddled with bolter fire. We could not guess how long they had lain there - perhaps since the hulk had last entered normal space. It might have been ten years or ten thousand - we did not know. The tides of warp space are unpredictable, and time flows strangely there.

"Brother Sergeant Conrad ordered us to be wary. Then a terrible thing occurred. A Space Wolf's corpse sat upright. its eyes glowing crimson. 'You are doomed.' it told us. 'Every one of you will die as I have.' We riddled it with fire from our weapons, but still its horrible whispers echoed in our minds.

"We began to fall back. All around us, Blips suddenly appeared on our sensors. They were running parallel to us, trying to cut us off from the boarding torpedo.

"At corridor intersections, we caught sight of armoured figures. We exchanged a few shots with them. I hit one and heard its scream over the comm-link. They were using the same frequencies as we were. When we realised that, our blood ran cold. We asked ourselves: could these be Marines?

'We did not have long to wait for an answer. They swarmed down the corridor toward us in a vast wave. They were garbed in the armour of Marines, but they were horribly mutated. Some clutched rusty bolters in tentacles instead of hands. Some had faces that were moist and green and slimy like toads. Some had claws and extra limbs. Some dragged themselves along, leaving a trail of mucus behind them.

"The mark of Chaos was upon them. They called on Horus and those powers that are better not named. And we knew then - they were renegades, survivors from the Age of Heresy who had pacted with Chaos in exchange for eternal life. The fighting became close and heavy. They had the weight of numbers, but we had our Terminator armour and the strength of righteousness.

"For a moment, it looked as though they might overwhelm us, but then our thunder hammers and lightning claws came into play, and we cut through them inexorably. They fought like daemons, and they had the strength of the damned, but eventually we won.

"I stood looking down at the body of my last foe, and a thought occurred to me: this man had once been a Marine like myself. He had undergone the same training and indoctrination as I had. He had sworn to serve the Emperor. And yet he had betrayed humanity. How could this be?

"How could a true Marine become forsworn? It seemed unlikely that he would suddenly turn his back on the pattern of a lifetime and pact with the Darkness. What had Chaos to offer him?

"Wealth? We have no use for the baubles that other men covet; we already have the finest of everything that a man could wish for. Sensual gratification? We are taught its transitory nature. Power? We know true power, which is the will of the Emperor. Who among us could equal his sacrifice?"

"No - as I stood over his body I came to understand. He had deviated not in one leap but in small steps, by increments.

"First he had come to place trust in the Warmaster. An easy step, for was not Horus the chief champion of the