It seemed inconceivable to him that Luther had missed the signs for so long. He was justly famous for his intellect, one of the very few on Caliban who could converse with Jonson on an almost equal footing. Zahariel knew that Luther monitored the reports of the Administratum, the local militia and the constabulary as a matter of course - it was part of his duties as the master of Caliban. If the threat was obvious to him, it should have been glaringly so to a man like Luther. The implications were disturbing, to say the least.

Zahariel wished there was someone he could talk to about his concerns. More than once he'd been tempted to bring the matter up to Brother Israfael, but the Librarian's stern and aloof demeanour had persuaded him against it. The only other member of the Legion he felt he could talk to had been Master Remiel, and now he was gone.

The young Librarian cast his eyes skyward and found himself wishing, once again, that Nemiel had been sent home as well. Zahariel thought his cousin could be overly cynical at times, but right now he needed a pragmatic perspective more than anything else. As much as he wanted to believe that Luther was still a noble and virtuous knight at heart, Zahariel had a sacred duty to his Legion, his primarch, and above all, the Emperor himself. If there was corruption within the ranks he was obligated to do something about it, regardless of who might be involved, but he had to be absolutely certain before he took action. Morale among the brothers was tenuous enough as it was.

Once again, Zahariel breathed deeply and tried to focus once more on his meditations. He closed his eyes, summoning up the mental rotes that Israfael had taught him, if only to drive away the worries that gnawed at his heart. He ruthlessly pushed conscious thought aside and emptied his mind.

The ghostly wind gusted once more, surprising him with its strength. Invisible and insubstantial, it nevertheless pushed roughly against him. The force of it rocked him back on his heels; without thinking, he opened his eyes and found himself staring into the face of the storm.

A pale blue glow suffused the courtyard, similar to moonlight but roiling like oil. Wild currents swirled and eddied around him, outlined in shades of black and grey; if he focused on them, they took on patterns that plucked uncomfortably at his mind. A faint, discordant moaning filled his head. The intensity of the vision startled the young Librarian for an instant. His concentration faltered - yet the sensations grew stronger.

Dark, hooded figures stirred at the edges of his sight, and then a voice, alien and yet chillingly familiar, echoed in his mind.

Remember your oath to us.

Zahariel let out a startled cry and spun on his heel, seeking the source of the voice. Memories of his quest for the Calibanite Lion, more than fifty years past, flooded back to him in an instant. He remembered wandering into a remote part of the forest more haunted and evil than he had ever known before, and the strange, hooded creatures who had confronted him there.

His hearts pounding wildly, Zahariel searched the courtyard's shadows for the Watchers in the Dark. The blue glow and the angry wind vanished from one blink to the next, and when his vision cleared, he found himself staring across the courtyard at the pensive figure of Luther. The master of Caliban was studying Zahariel intently.

'Is something wrong brother?' Luther said quietly. His voice was full of concern, but the knight's expression was inscrutable.

Zahariel mastered himself quickly, controlling the flow of adrenaline and lowering his heart rate with a few controlled breaths. 'Brother-Librarian Israfael would reprimand me for letting someone catch me unawares while I was meditating,' he said. It shocked him how quickly the lie came to his lips.

Silence fell between the two warriors. Luther studied Zahariel for a long moment, then smiled ruefully. 'We've all got a lot on our minds these days, haven't we?'

'More so than ever before,' Zahariel managed to say.

Luther nodded in agreement. He crossed the courtyard quickly, his manner formal but his expression still guarded. 'I've been looking all over the fortress for you,' he said.

Zahariel frowned. 'Why didn't you contact me on the vox?'

'Because some conversations don't belong on the network,' Luther replied in a low voice. 'I'm about to attend a very important meeting, and I want you there as well.'

The Librarian's frown deepened. 'Of course,' he replied at once. Then, more hesitantly, he said, 'The hour is very late, brother. What's this about? Has something happened?'

Luther's handsome face turned grim. 'An hour ago, insurgents launched attacks on foundries, manufactories and Administratum buildings all over Caliban,' he said. 'Since then, riots have broken out in a number of arcologies, including the new one up in the Northwilds.' His lip curled in an angry snarl. 'The constabulary has been unable to deal with the crisis, so I've despatched ten regiments of Jaegers to restore order.'

The news stunned Zahariel. Suddenly, Luther's decision to withhold the Legion's reinforcements seemed almost prescient. The insurgency on Caliban had entered a dangerous new phase. His mind began to race, recalling reams of data on combat readiness, deployment times and logistics requirements for the Astartes chapters and support units on-planet. 'Will this be an operational meeting, or a strategic one?' he asked. 'I'll need a few minutes to collect the proper data files.'

'Neither,' Luther replied. His expression became guarded. 'The rebel leaders have been in contact with Lord Cypher. They want to meet with me under a flag of parley, and I've agreed. They'll arrive within the hour.'

The shuttle was a standard Imperial design, anonymous and unnoticed among the hundreds of craft coming and going from the landing fields around Aldurukh. At precisely two hours past midnight, the transport touched down and lowered its landing ramp. Its engines subsided to an idle hum as five individuals moved quickly and purposefully down the ramp and crossed the permacrete towards the open doorway of a nearby hangar. They entered the cavernous space warily, scanning the deep shadows for potential threats. Finding none, the rebel leaders and their lone escort crossed to the centre of the building, where Luther and Zahariel stood in the glow of one of the hangar's many floodlights.

Zahariel watched the traitors approach and tried to remain outwardly calm. His mind was in turmoil, torn between outrage and obedience. Luther's decision to meet with the leaders of the insurrection shocked him to the core; it went against everything the Legion had taught him. Defiance of Imperial law demanded swift and ruthless action, without mercy or compromise. Negotiation of any kind was unthinkable, and threatened to undermine the Emperor's authority. Entire worlds had been devastated for less.

But this wasn't some strange, isolated planet like Sarosh. This was Caliban. These were his people, and Zahariel knew in his heart that they weren't corrupt or evil. Perhaps that was what was foremost in Luther's mind as well, he thought. It served no one, least of all the Emperor, if millions of innocent lives were lost thanks to the actions of a misguided few. And if anyone could convince these men to abandon their cause, it was Luther. So Zahariel told himself, and tried to master the doubts that gnawed at his heart.

The five figures each wore an aspirant's hooded surplice, hiding their faces in shadow. None of them were armed, as the ancient traditions of parley demanded. As they stepped into the circle of light, Zahariel felt a rising pain in the back of his head. His vision wavered; the hooded figures seemed to double before his eyes, and the light flickered strangely. The Librarian screwed his eyes shut and used the rotes he'd learned from Israfael to try and clear his mind. When he opened them again, his vision was clear, but the pain refused to go away.