Luther nodded. 'What about industrial sites?'

'We've had much better luck there,' Morten continued. 'The larger manufactories and mining outposts have been assigned a small garrison for security, with mobile reaction forces standing by to provide reinforcement in case of an attack. As a result, we've managed to defeat a number of major attacks over the course of the last few days.'

'Although it appears that the rebels feel confident enough to start sniping at transports and shuttles coming and going from Aldurukh itself,' Bosk complained. Not half an hour after Epsilon Three-Niner's narrow escape, Bosk's shuttle had been briefly targeted by a rebel autocannon on its approach to the fortress. 'Who are these criminals, and how have they managed to accomplish so much in so little time?'

Luther took a deep breath, clearly choosing his words carefully. 'There are indications that the rebels are made up mostly of disaffected nobles and former knights. We believe they've been laying the groundwork for this campaign for many years, stockpiling weapons and organising their forces.'

'Their discipline is impressive,' Morten said grudgingly. 'And their organisation is highly decentralised. I have no proof, but I strongly suspect that one or more of their senior leaders have received Imperial military training at some point. We haven't been able to gather any useful intelligence on their command and communications network, much less identify any of their leaders.'

Zahariel eyed Luther intently, wondering if he would identify Lord Thuriel and the other rebel leaders, but the knight said nothing.

'What do these criminals want?' Bosk demanded.

Luther regarded the magos inscrutably. 'They want to be relevant once more,' he said.

'Then they can go to work in a munitions plant,' Bosk snapped. 'This planet has obligations - strict obligations - to the Emperor's forces, and it's my responsibility to make sure those obligations are met. What's being done to round up these ringleaders and deal with them?'

Morten sighed. 'That's easier said than done, magos. My troops are already stretched to the limit maintaining order and protecting your industrial sites.'

'Which are sitting idle because there aren't any labourers to man the assembly lines,' Bosk retorted. 'They can't leave their hab units while martial law is in effect.' Layers of fabric rustled as the magos folded her thin arms and glared at Luther. 'Where is the Legion in all this, Master Luther? Why haven't they been unleashed against the rebels?'

Zahariel straightened. Bosk had cut to the heart of the matter. Now perhaps they would hear the truth.

Luther leaned forward, resting his forearms on the massive oak desk, and met the administrator's stare unflinchingly. 'Administrator, my battle brothers are capable of a great many things, but hunting criminals isn't one of them. When the time is right and the proper targets present themselves, the Dark Angels will act - but not before.'

Magos Bosk stiffened at Luther's reply. 'That won't do, Master Luther,' she said curtly. 'This unrest must stop immediately. Caliban's obligations must be fulfilled without delay. If you won't act, then I'll be forced to report the situation to Primarch Jonson and to the Adeptus Terra.'

The air in the chamber was suddenly charged with tension. Luther's gaze turned hard and cold. Zahariel started to step in and try to defuse the situation when the door to the chamber opened and one of Morten's aides hurried inside. With an apologetic bow to Luther, the aide turned to the General and whispered urgently into his ear. Morten frowned, then began asking the aide a number of increasingly urgent questions. Magos Bosk watched the exchange with growing alarm.

'What's happened?' she asked, her metal-clad fingers clicking as she gripped the wooden arms of her chair. 'General Morten? What's going on?'

Morten waved his aide away. He looked questioningly at Luther, who gave his permission with a curt wave of his hand. The general took a deep breath, and addressed the magos.

'There's been… an incident at Sigma Five-One-Seven,' he said.

'An incident?' Bosk said, her voice rising. 'You mean an attack?'

'Possibly,' the general replied. 'At this point we don't know for certain.'

'Well, what exactly do you know?'

Morten couldn't entirely suppress a frown of irritation at the administrator's demanding tone. He related what he knew in a clipped, businesslike manner. 'Approximately forty-eight minutes ago our headquarters received a garbled transmission from the garrison at Sigma Five-One-Seven. The vox operator confirmed that the signaller was using the garrison's proper callsign and encryption code, but couldn't make out what he was trying to say. The transmission lasted thirty-two seconds before being cut off. Nothing has been heard from the garrison since.'

'Jamming?' Luther inquired.

Morten shook his head. 'No sir. The transmission simply stopped. The signaller was cut off in mid-sentence.'

The Master of Caliban turned his attention back to Magos Bosk. 'What exactly is Sigma Five-One-Seven?'

'A materials processing plant in the Northwilds,' she replied. 'It went online last month, and has yet to become fully operational.'

'How many labourers?'

'Four thousand per shift under normal conditions, but as I said, the plant wasn't operational.' Bosk pursed her lips as she accessed her cortical data shunts. 'There were difficulties with the plant's thermal power core. An engineering team was on site, trying to track down the source of the problem, but that was all.'

Luther nodded. 'And the garrison?'

'A platoon of Jaegers and an attached heavy weapons squad,' Morten answered. 'Enough to defend the site against anything but a major rebel attack.'

'Well, obviously that's exactly what happened,' Bosk snapped. 'You said you had mobile troops to reinforce the garrisons in the event of attack. Why haven't you despatched them?'

The general glowered at Bosk. 'We did, magos. They landed at the site five minutes ago.'

'Well, what in the Emperor's name did they find?' Bosk demanded.

Morten's expression turned grim. 'We don't know,' he said reluctantly. 'We lost all contact with them moments after they touched down.'

Luther sat bolt upright in the Grand Master's chair. Zahariel felt a wave of unease wash over him; something very strange was going on. From the dark look in Luther's eyes, it was clear that the Master of Caliban felt much the same.

'How large was the relief force?' Luther asked.

'A reinforced company,' Morten replied. 'Two hundred men, plus heavy weapons and ten Condor airborne assault carriers.'

Zahariel's unease deepened. 'A force that size would have been more than enough to deal with any rebel attack. 'It's possible that the original transmission was a ruse, and the relief force was lured into an ambush.'

'It's possible,' Luther said, somewhat dubiously. 'But why no vox signals? Surely we would have heard something.' He turned to Morten. 'Are there any other reaction forces in the area?'

'The closest one is more than two hours away,' the general replied. 'I can divert them to the site, but it would leave the Red Hills sector without any reinforcements in the event of another attack.'

Bosk rose angrily to her feet. 'This is outrageous,' she declared. 'Master Luther, I mean you no disrespect, but I have to report this to Primarch Jonson and my superiors on Terra. The situation is worsening by the moment, and it's obvious to me that you're unwilling to commit your Astartes in battle against your own people. Perhaps forces from another Legion can be despatched to put an end to the uprising.'

Luther's handsome face paled with anger. General Morten saw the danger and began to stammer a quick reply, but Zahariel cut him off.