THE YEARS LAY SO heavily on the corridors of the Librarium Terra that the very air was thick with age. The endless tottering rows of bookcases and verdi-grised datastacks seemed chained down by the weight of the thousands upon thousands of years of history. The librarium was deep within the planet's crust but even som the indistinct hum of activity droned through the labyrinthine corridors, just as it did everywhere else on the holy hive world of Terra. It was the sound of billions of souls grinding their way through the bureaucracy that kept the Imperium of Man together.

Even the captain of the deletions unit felt the sheer importance of the information that filled the librarium. He had lived on Terra all his life, immersed in the endless repetition of the myriad tasks that made up the government of the Imperium. He had done his job since birth, just as his forebears had done, and the shadows beneath Terra comprised his whole world.

But even he, after the decades spent performing his thankless task, had some instinctive understanding that the Librarium Terra held a repository of particularly pure, dangerous history.

The captain glanced around the next corner. The gallery he saw was lined with shelves of books so old they were little more than banks of rotting paper, lit by yellowed glow-globes that picked out the faint silver spider's webs that had been there, undisturbed, for as long as some of the books.

No one knew the full layout of the Librarium Terra. Estimates of its size varied, as no one had been to its furthest extents and returned - the deletions team had taken three days of forced marching to get this far. But, by the best estimates of the adepts who gave the unit its orders, the objective was close by.

The captain waved his ten-strong unit forwards. They wore black bodysuits with hoods that left only the eyes visible, rebreathers built in to keep aeons of dust out of their lungs. Their gloved hands held narrow-nozzled flamers connected to fuel canisters on their belts. But the captain carried a silenced autogun with a flaring flash suppressor. They moved quickly and almost silently, each one covering the other. They had always been members of the same unit, just as the captain had always commanded them. The captain didn't need to actually give them orders - they just did as they had always done, as generations had done in the endless predator's game beneath Terra.

The captain hurried down the gallery until it opened onto a landing overlooking a tangled knot of bookcases and datastacks. The cases held huge leather-bound volumes, tarnished infoslates, crumbling scrolls and reams of parchments, crammed onto shelves that had collapsed here and there into drifts of tattered paper. The datastacks, blocks of smooth black crystalline material that could store remarkable amounts of information, ranged from sinister glossy black obelisks to elaborate info-altars covered in filigree decoration and crowned with clusters of statues. Several of them bore images of the Adeptus Astartes, the armour-clad Space Marines who formed the elite of the Imperium's armed forces, battling aliens and corruption across the distant stars.

The captain peered into the gloom that flooded the labyrinth below. He spotted movement - a scholar worked in an alcove formed by the cases. Surrounded by discarded books he was leafing rapidly through another. His face was incredibly wizened and his arms had been replaced with jointed metal armatures that flicked through the book's pages with incredible speed. The scholar could have been a servitor, a mind-wiped automaton that was human only in the sense that it was formed from a rebooted human brain. Or it could have been a sentient human, a loyal servant of Terra like the captain himself, acting out some task that was probably redundant and meaningless but which represented the loyalty of everyone on Terra to the immortal God-Emperor.

The captain raised his autogun close to his face and focused on the hairless, tight-skinned skull of the scholar. The autogun coughed once and the scholar's skull crumpled suddenly as if paper-thin. The body slumped and fell, sprawling against the shelf behind it and disappearing beneath a cascade of books.

There were to be no witnesses to a deletion. That was the way it had always been done. Had the scholar been aware of it, he would have understood why he had to die.

The captain vaulted from the balcony down into the shadows below. The rest of the unit followed him, their feet padding on the tarnished wood of the floor as they landed. Down here the air was so heavy with age and knowledge that moving around was like walking through water. The faint, sickly glow from the electro-lanterns dotted here and there served only to make the shadows harder. The captain spotted some titles and dates on the volumes on the shelves. These books held details of the Imperium's armed forces, regimental histories of the Imperial Guard and accounts of long-forgotten battles. The deaths of billions of men were glossed over in those pages, and the captain could almost hear them screaming from the same pages that praised their sacrifice to the Emperor.

A simple hand signal, and the deletions team spread out, each taking a section of bookshelf and pulling out volumes at random, glancing at the covers and contents and then casting them to the floor. A servitor appeared without warning, its deformed splay-fingered hands spinning along the floor in a fruitless attempt to keep it clean. The nearest of the unit turned, sprayed a lance of flame through its vulnerable soft human core, and turned back to his work as the servitor shuddered and died in a burst of sickly smoke.

Another unit member hurried up to the captain. He was holding a book of red leather, its pages edged in gold. On the cover was a raised symbol of glittering black stone - a chalice surrounded by a spiked halo. It was the symbol they had been ordered to look out for.

The captain tapped the nearest deletions trooper on the shoulder. The trooper then tapped the nearest to him, and the signal passed through the whole team in a heartbeat. They dropped whatever they were holding and drew their flamers.

They fired plumes of flame into the bookshelves, filling the power-charged air of the Librarium Terra with the stink of flame and smoke. The protective clothing of the team reflected the worst of the heat but the labyrinth was still a furnace, with walls of superheated air billowing between the burning cases.

The captain removed the magazine of his autogun and replaced it with a single round picked from his belt. He aimed at the closest datastack, which was shaped like a three-panelled altarpiece with its mem-crystal worked into heroic images of battle. The gun fired again, with barely a sound, and the explosive round shattered the crystal into a flood of broken black glass.

Wordlessly, with an efficiency born of generations of toil, the deletions unit moved through the whole section of the library burning and shattering anything that might hold the information they had been ordered to destroy. Already the energy suppression drones were hovering in from around every corner, projecting dampener fields that held back the heat of the fires and kept them from spreading. When the team left, the drones would move in and their overlapping fields would smother the flames - but not before the books and datas-tacks were reduced to smoke and ash.

Centuries of history were lost. Whole planets and military campaigns vanished forever from the Imperial memory. But more importantly by far, the deletion order had been carried out, and all official record of the Soul Drinkers Chapter was erased from the history of Mankind.