The watchers studied him for a long moment, while the ghostly winds of the immaterium howled above their heads. Then, slowly, the watcher in the centre shook his cowled head.

In that you are wrong, Zahariel of the Dark Angels, the watcher replied. Its unearthly voice was low, and almost sad. Caliban is doomed, and nothing you do can prevent it.

Zahariel blinked in surprise, stunned by the watcher's words. When he opened his eyelids again, the afterimage of the lightning bolt was fading from his vision. Rain smote his face, and the Watchers in the Dark were gone.

Zahariel burst into the Grand Master's sanctum unannounced, the thick, oaken door rebounding with a boom from the old stone walls. Lord Cypher looked up from behind the Grand Master's desk, his hooded form bent over neatly-stacked data slates and copies of readiness reports.

The enigmatic Astartes' square-jawed face betrayed no emotion at the Librarian's sudden arrival. 'Master Luther remains in seclusion, meditating on the crisis,' he said coolly. 'Have you another message for me to deliver?'

'I'm not looking for Master Luther,' Zahariel said, stalking purposefully across the room. 'You're the one I wish to speak to, my lord.'

'Indeed?' Cypher straightened, hooking his thumbs casually in his tooled leather gun belt. 'And how may I be of service, Brother-Librarian Zahariel?'

'I want another parley with the rebel leaders,' Zahariel said. 'Specifically Sar Daviel. And it needs to be within the next twenty-four hours.'

The request seemed to genuinely amuse Cypher. 'Shall I pull the moon out of the sky while I'm at it?' he asked with a faint grin.

'You got word to them once before,' Zahariel continued stubbornly. 'I have no doubt those channels are still open to you, if you choose to employ them.'

The traditions of parley went back for hundreds of years on Caliban, when open warfare between knightly orders was more common. Even the bitterest foes maintained channels of communication to facilitate negotiations or declarations of surrender. It was a means of avoiding unnecessary casualties and bringing a swift end to open combat before both sides were too badly mauled to perform their sworn duty to the people of Caliban.

The grin faded from Lord Cypher's face. His lips pressed into a narrow line. 'Only the Grand Master can initiate a parley,' he said.

'Not so,' Zahariel countered. 'Astelan and I are his designated representatives, and so long as he remains incommunicado, we have the authority to prosecute the war as we see fit. And I wish to parley with the rebels at once.'

Lord Cypher hesitated for a moment, but then ultimately gave a nod of assent. 'The rebels won't agree to a meeting at Aldurukh this time,' he warned.

'I've no interest in speaking to them here,' Zahariel said. 'Tell Sar Daviel that I will meet them at a place of their choosing,' he said, 'inside the Northwilds arcology. No other location is acceptable.'

Cypher studied Zahariel closely. 'An unusual request,' he said. 'They will want to know why.'

'Because the fate of our world is going to be decided there,' Zahariel replied. 'Whether any of us like it or not.'

FIFTEEN

Engines of War

The forge's massive Titan foundry was actually a collection of cyclopean structures that filled an area of five square kilometres, not far from the complex's southern gate. It was a self-contained manufactory, with facilities for creating everything from adamantine skeletal segments to tempered plasteel armour plate, and everything in between. Broad trackways, made to accommodate heavy load-haulers, connected to the towering structure at the centre of the foundry: the giant assembly building, where up to four of the gargantuan war machines could be built at the same time. When a Titan was completed it would then be handed over to the adepts of the Legio Gladius with solemn ceremony, and the engine would take its first steps to join its brethren at the legion's fortress, some ten kilometres to the north.

Nemiel and his squad encountered the first of the skitarii patrols at the edge of the foundry sector; these were well-equipped troops in static positions, manning lascannons or heavy stubbers and sweeping the perimeter every few seconds with advanced auspex arrays.

He halted the squad in the shadow of an idle manufactory and waved Brother Askelon over. 'It looks like the assembly building is the only part of the foundry in operation,' he said, nodding towards the towering well-lit structure. 'Magos Archoi isn't taking any chances. He's extended his security perimeter to the very edge of the sector. Can you think of a way we can get past those auspex units? It's imperative we find out what Archoi is doing.'

The Techmarine considered the problem for a moment, and nodded. 'All of the facilities here are powered by the thermal reactors inside the volcano,' he said. 'The power feeds are run through utility tunnels that connect all the buildings. They'll likely be covered by automated security systems, but I believe I can bypass them.'

Nemiel nodded. 'Let's go. We don't have much time until dawn.'

Askelon led the squad back the way they'd come, to an access door at the far side of the manufactory. While Nemiel and the rest of the Dark Angels stood watch for more Mechanicum patrols, the Techmarine bypassed the door's security system and slipped inside. Fifteen seconds later he returned, beckoning for Nemiel. 'There are several small, cybernetic sentries prowling the building,' Askelon whispered. 'They follow predictable routes and use their surveyors to scan for signs of heat or motion, but they're very short-ranged. Stay close, and move only when I say.'

The Techmarine led the squad across the dark floor of the manufactory, slipping between massive stamping machines and automated spot-welding arrays. Askelon traced a winding, deliberate route through the plant, pausing at times and listening for the telltale ultrasonic whine of an auspex transmitter. After several long minutes they reached a short, squat permacrete structure at the centre of the manufactory floor. Askelon located a plasteel door in the side of the structure and quickly disarmed its sensors, then led the squad inside. Within, a cluster of giant, metal-clad conduits rose like fat, silver worms from a circular hole in the middle of the bare permacrete floor and connected to large junction boxes on three of the four walls. Control panels along the wall beside the door monitored the power feed to the manufactory's systems.

Askelon stepped to the edge of the hole and located a set of metal rungs that descended into the access tunnel below. Hot, dry air, smelling of ozone and sulphur, wafted up from the depths. 'We'll follow the tunnel to the access point underneath the assembly building,' he said to the squad. 'Keep your eyes open, brothers. There may be cybernetic sentries in the tunnel as well.'

'What do we do if we see one?' Kohl asked.

'Shoot it,' the Techmarine replied with a shrug, 'and hope that it can't get a signal off before it's destroyed.'

Kohl and Nemiel exchanged grim looks and followed Askelon down into the tunnel.

The utility tunnel was tall and wide, its circular walls lined with thick, metal conduits stamped with strings of binaric code. The Techmarine headed off down the tunnel in the general direction of the foundry, pausing from time to time to read the stamps on several of the conduits to his left.

They travelled for more than two kilometres, following the trunk labels through one intersection after another. Finally, Askelon battle-signed for the squad to halt and sank slowly into a crouch.