Zahariel could understand how such a thing could be done. He just couldn't figure out why. An attack of this kind didn't match the insurgents' tactics to date, and it seemed like a disproportionate investment of time and manpower on a target that was far from any of the planet's major population centres. So far, the rebels were doing a very effective job of crippling the planet's industrial base by fomenting riots in the arcologies and staging hit-and-run raids with small, well-armed guerrilla forces. And this particular plant was sitting idle anyway; Zahariel could think of a dozen targets offhand that would have made better candidates for a takeover. There was a great deal about the situation that didn't add up, and he wasn't heading back to Aldurukh until he had some answers in hand.

The voice of the Land Raider's driver crackled over Zahariel's vox-bead. 'Coming up on the site's main gate now,' he said. 'Orders?'

'Increase speed,' Zahariel replied. 'Advance up the main road towards the central landing zone.'

The assault tank's engine roared in reply, and the Astartes in the troop compartment swayed in their seats as the Land Raider surged forward. The vehicle struck the plant's heavy main gate and crumpled it contemptuously. Zahariel heard the faint clang of the impact and the screech of metal as the broken gate was ground beneath the heavy tank's treads, but the barrier scarcely slowed the Land Raider down. As the tank roared along the main road, he switched to the Legion command frequency and reported in to Aldurukh. 'Seraphim, this is Angelus Six,' he called. 'We have reached Objective Alpha and are proceeding to secure the area.'

The reply came back at once. Zahariel was surprised to hear Luther's voice over the vox instead of the strategium's duty officer. 'We read you, Angelus Six. Any sign of the garrison or the relief force?'

'Negative,' Zahariel replied. 'No obvious signs of combat, either. I expect I'll learn more once I reach the central landing zone.'

'Understood,' Luther said. 'Broadsword Flight is on station and standing by if you require support, Angelus Six. Remain in contact at all times.'

The Librarian twisted a dial on the tactical display and brought up a regional map of the Northwilds sector. A green diamond, representing the transport craft that had delivered the Land Raider from Aldurukh was shown exiting the area to the south. There was also a small, red chevron blinking above the mountains northwest of the site, flying in a circular holding pattern between Sigma Five-One-Seven and the recently established Northwilds arcology. The alphanumeric code beneath the chevron told him that Broadsword Flight consisted of three Stormbirds, each loaded with a full suite of air-to-ground ordnance. Luther had put enough firepower at his disposal to destroy an entire armoured regiment. Zahariel was more grateful for the obvious sign of Luther's support than the Stormbirds themselves. 'Understood, Seraphim,' he answered. 'We will keep you advised.'

Zahariel switched the tactical display back to the tank's forward auspex array, then turned away from the screen and bent in his seat to pick his helmet off the Land Raider's deck. 'We're coming up on the edge of the objective area,' he said, pitching his voice to cany over the tank's roaring engine. 'Prepare to deploy. Brother Attias, take the pintle mount.'

Silent and purposeful, the veteran squad fitted on their helmets and checked their weapon loads. Across from Zahariel, Chapter Master Astelan readied his bolt pistol and power sword. When the order had come down to assemble a combat patrol to investigate the site, Astelan had been among the first to volunteer. After nearly a half-century in garrison, every member of Luther's training cadre was eager for action, and Zahariel was glad to have a warrior of Astelan's ability as part of the squad.

At the far end of the troop compartment, Brother Attias rose to his feet and worked his way down the narrow aisle between his squadmates. Attias had been an aspirant of the Order at the same time as Zahariel and Nemiel, and as a youth he'd earned no small amount of grief thanks to his nervous and overly-studious nature. That had changed on Sarosh, when an alien monster had melted his helmet with a torrent of caustic slime. Attias had been lucky to survive, but the Legion Apothecaries had been powerless to heal the damage wrought by the monster's acid. In the end, they had been forced to strip away most of the flesh and muscle and graft polished steel plates directly to Attias's skull, transforming his face into a gleaming death mask. After more than a year recovering from his wounds, he had joined Astelan's training cadre, where he was roundly feared by the chapter's novices. Zahariel had barely spoken to him in the years since returning to Caliban. Outside of training, Attias rarely spoke to anyone at all.

Zahariel watched as Attias stepped past him and took up the remote controls for the Land Raider's pintle-mounted storm bolter. Servo-motors whined on the tank's roof as the weapon elevated and began to cover the rooftops of the plant's outer buildings as they made their way deeper into the site. The heavily-armoured Land Raider was impervious to all but the most powerful anti-tank weapons, but in the confines of the industrial plant a rebel team with melta bombs - or worse, a meltagun - could be a serious threat.

For several minutes there was nothing to do but wait. Zahariel reached over and undipped his force staff from where it hung against the tank's armoured bulkhead and gripped the cold, adamantine haft with both hands. The staff was both a weapon and a focus for the Librarian's psychic abilities, and Zahariel took a moment to meditate upon it as Israfael had taught him to do. He began with a series of slow, steady breaths as he interfaced first with the crystalline array of the psychic hood built into his power armour. The array, built into a metal shell that rose from the back of his cuirass and partially enclosed his bare head, served as a crucial buffer that shielded his brain from the terrible energies of the warp. Without it, he risked madness - or worse - every time he unleashed his psychic powers in battle.

The interface cables connecting Zahariel to the hood grew warm against the back of his skull as he accessed the array and focused his awareness on the staff. Only then, once he was firmly grounded, did he extend that awareness further and take the measure of the psychic energies surrounding Sigma Five-One-Seven.

The shock was like an icy gale against his skin. Zahariel felt his flesh prickle; his muscles tensed, and a hungry, howling wind thundered in his mind. He felt the crystal array behind his head grow hot as the psychic torrent threatened to overwhelm the hood's dampeners. It was like the raging storm he'd experienced at Aldurukh, only far stronger and wilder. What was worse, the Librarian could feel an otherworldly wrongness about the tempest - a taint that seemed to tug at his very soul.

Zahariel recoiled inwardly from the shock of the psychic storm. Screwing his eyes shut, he drew back his awareness as swiftly as he could, but the vileness in the aether plucked at him like grasping tendrils. For a horrifying second it felt as though there was a sentience behind the psychic force, and he was reminded of the nightmarish spectacle he'd witnessed on Sarosh.

After what seemed like an eternity, he managed to pull himself free from the taint. It withdrew and left him shaken to his core.

'Are you well, brother?'

Zahariel looked up and saw Astelan's concerned expression. He nodded, catching his breath. 'Of course,' he replied, 'merely focusing my thoughts.'

The chapter master raised a dark eyebrow. 'They must be very weighty thoughts. I can see the pulse in your temples from here.'

Zahariel wasn't certain how to respond. Did he share what he'd just experienced? Would it make any difference to Astelan or the rest of the squad? This was a situation he'd never experienced in any training scenario. The matter was taken from his hands, however, when suddenly the driver called out over the intercom. 'We've reached the central landing zone. I see ten Condor aerial transports in tactical landing formation at one hundred and fifty metres.'