Norroll’s tongue clove to the roof of his mouth. It happened every time Fennech came near or addressed him, plunging him back into the fears and vulnerabilities of his childhood.

  It was the same for the others. Norroll wondered how Traxel remained so aloof. Of all the Scions who had encountered Fennech at the scholam, Traxel seemed least affected by the air of menace the commissar engendered.

  ‘It is possible, commissar,’ Traxel said.

  Norroll smirked beneath his respirator as the realisation struck him.

  Traxel was unfailingly polite in his discourse with Fennech, which was in itself remarkable. Over two years, Norroll had come to know the Tempestor as a habitually blunt soul, entirely devoid of non-regulatory courtesy. Contrasted against his natural deportment, this alien formality accentuated the depth of the fear Traxel bore for his old discipline master. Decorum set a hard distance between the two, keeping Traxel as far from Fennech as he could manage, while still giving him a means to navigate his fear.

  Norroll pushed the observation aside for later consideration and internalisation. ‘There’s a large energy source towards the centre of the facility,’ he said. ‘Likely the main reactor.’

  ‘If we shut it down, we stand to shut down the signal dome,’ Traxel said as Actis floated past him, returning to Norroll. ‘Mark it as our secondary objective. Any sign of the Space Marine?’

  ‘No, Tempestor. He could be anywhere.’

  ‘Daviland?’ Traxel called.

  ‘Two minutes, Tempestor,’ Daviland called back as she tied down a dressing on Durlo’s outer right thigh.

  ‘We move in one,’ Traxel said. He turned back to Norroll. ‘Scout ahead, mark defences and find us a way to that power source. It stands to reason that the Iron Warrior will be close by it.’

  ‘Aye, Tempestor.’

  ‘And Norroll?’ Traxel added. ‘Nothing stupid.’

  ‘No promises, Tempestor,’ Norroll scoffed. Blunt, indeed.

  Norroll crept down the curving passage, laspistol and monoblade at the ready, heart pumping in anticipation of meeting an enemy his augurs told him wasn’t there. He marked the first junction on his slate and turned down into another corridor, identical to the first but for its orange-painted walls. Sentry guns were mounted to the ceiling, ten yards inside the corridor on either side of the junction, their turrets describing a slow, lazy circuit.

  ‘Multi-laser turrets on either side of the junction for reduction,’ he whispered into the vox.

  ‘Understood.’

  First Eradicant filed into the junction behind him. Traxel crawled forward on Norroll’s signal, observing the turrets for a moment. He traced a half-rectangle in the air with his index fingers, then brought his hand down in a diagonal chopping motion.

  Durlo shook his head, flicking his hand horizontally to indicate he was out of demolitions equipment.

  Traxel signalled Bissot and Rybak forward.

  The turrets were synchronised so that one covered the junction when the other faced down the hall, but there was a brief, exploitable delay in coverage between them. The Scions leapt into the corridor when they would both be in the turrets’ blind spots, Bissot left and Rybak right, angling their weapons up and firing. Bissot stilled her turret with a volley of hotshot las-fire, while Rybak’s plasma gun destroyed the other in a flash of fire and shrapnel.

  Norroll led the Tempestus Scions deeper into the complex.

  The automated turrets were a recent addition to the network of concentric corridors, which had apparently been built ages before with the intention of carrying on military operations in the event of a catastrophic surface war. Each junction between the coaxial hoops of corridor could be sealed by heavy durasteel airlocks, which proved impervious to repeated strikes from Commissar Fennech’s power fist. The Scions were forced to weave up and down through multiple layers of the complex, often doubling back as they found doors which had previously been open now closed.

  Norroll leaned against a blast hatch, staring at his wrist-slate. They had wandered through the entire bunker twice, and Actis had led them here, to the bottom of the fourth sublevel, each time. He tore open his faceguard and took a deep breath, tasting the ozone in the processed, heavily recycled air. He hissed the breath out in frustration.

  ‘Here,’ he said, rapping on the door. A red placard, marked with the black-and-white-partitioned skull-on-cog symbol of the Adeptus Mechanicus, advised: Warning – Plasma reactor. Failure to observe proper rites before opening hatch could incur the Omnissiah’s wrath.

  ‘We’ve been here before,’ Phed said.

  ‘No, we haven’t. We were on the other side before. I marked the wall. Core vault, level five. Actis led us here because the reactor is behind. The damned. Door!’ He punched the door three times for emphasis. He roared in frustration, not pain – like all Scions, Norroll had been striking steel plate at full strength in conditioning exercises since before he was a teenager.

  ‘There’s no other way in?’ Durlo asked.

  Norroll shrugged. ‘No idea. Maybe there’s another. We just have to wander through the never-ending bunker again for Emperor knows however long until we find it.’

  ‘It’ll probably be closed, too,’ Rybak grumbled.

  ‘How many plasma flasks do you have, Rybak?’ Durlo asked.

  ‘Two. Why?’

  Durlo held out his hand. ‘Give them to me.’

  ‘I have five shots left on this flask.’

  ‘Overkill. You only need one,’ Durlo said, pointing to the gold marksmanship badge on Rybak’s left pectoral.

  ‘Durlo, no–’

  ‘Give him the flasks, Rybak,’ Traxel ordered.

  Rybak pulled two plasma flasks from his belt pouches and slapped them roughly into Durlo’s hands.

  ‘I’m also going to need your dynamo and capacitor batteries.’

  ‘What?’

  ‘You’re the only one here besides the Tempestor with capacitors and no lasgun,’ Durlo explained.

  ‘Give it to him, Rybak,’ Traxel said. ‘You can lug mine around if you still want to carry the weight.’

  ‘No, Tempestor. Thank you.’

  Durlo helped decouple Rybak’s gear from the frame of his backpack, then hauled the capacitor unit and plasma flasks to the door. Shrugging off his own backpack, Durlo opened his toolkit. ‘You may as well get comfortable. This will take some time.’ He paused. ‘I also recommend everybody clear out of the immediate area, just in case something goes amiss.’

  ‘Is there a large chance of that?’ Traxel asked.

  Durlo shrugged. ‘The fellow who taught me this died while he was demonstrating it to me, but I view that as more an example of what not to do.’

  ‘You’ve tried this before, though?’ Bissot mumbled around a mouthful of dry nutri-wafer, her faceguard hanging open.

  ‘No, but I understand it in principle well enough.’

  The Scions retreated without another word, leaving the demolitions trooper to his work. The quiet clinking and snipping of Durlo’s labours trickled down the corridor to them, and Norroll gnawed on a strip of freeze-dried grox meat as he patched his fatigues, occasionally catching individual words and muttered fragments of prayer from Durlo.

  Daviland took advantage of the time to check up on the Scions, who busied themselves with weapons maintenance, eating and meditation. Fennech cleaned his bolt pistol, the components delicate in the thick fingers of his power fist as he ran a wire brush down the barrel.

  ‘Helmets on, get down!’ Durlo called down the hall. ‘Also, prayers would be appreciated.’ He gave them a short time to ready themselves. ‘Ready in three… two… one…’

  A moment later and he charged into the midst of them, ducking around the bend in the passageway and dropping low.

  The heat wash from the explosion seared down the corridor, accompanied by a thunderous blast of overpressure that buffeted the Scions where they crouched. A roiling mist boiled along the passage, laden with the chemical stink of burned plastek and the sharp tang of superheated metal. They picked themselves up, their rebreathers filtering the metallic particulate from the air. Warning klaxons howled from within the reactor room.

  Durlo’s makeshift explosive had bored a hole through the bottom centre of the door, the uncontained plasma reaction evaporating an area of nearly three feet square and reducing the edges of the rent to glowing slag. The reinforced rockcrete floor beneath the door had likewise been rendered to incandescent slurry. The tiles nearest the door had been boiled away, and even the ones several feet away curled up from the floor, blackened and blistered. A cloud of white mist hazed through the hole, sizzling as it contacted the superheated material and leaving a crust of blackened crystals in its wake.

  ‘Keep clear of the mist,’ Durlo said. ‘It will freeze you solid.’

  Phed eyed the tendrils of mist coiling around the base of the door warily. ‘What is it?’

  ‘You’d have to ask the tech-priests,’ Durlo admitted, ‘but I had expected it. It’s a countermeasure for the reactor, to keep temperatures from getting too high. It should stop when the internal temperature drops enough. Norroll, have Actis monitor the temperature of the reactor room. We’ll be able to get inside when entry would be survivable.’

  ‘What happened to my generator unit?’ Rybak asked.

  ‘Thank the Emperor for your respirator, or you’d be breathing it,’ Durlo said.

  The destruction of the plasma reactor plunged the fortress into unbroken, caliginous darkness. Despite this, First Eradicant unerringly navigated the bunker complex, their helms’ low-light filters harnessing the scant illumination emitted from their weapons’ status lumens and vambraces to cast the world in hues of static-laden green. They ascended rapidly, the turrets which had vexed them in their progress earlier rendered inert by the blackout, using the markings Norroll had left earlier and Actis’ augurs to guide them ever upwards. In short order, they achieved the complex’s first sublevel and began the circuit through the outer rings.

  Akraatumo pressed his helm’s right earpiece. ‘Vox is operational,’ he reported, unhooking the clarion’s handset from where it lay clipped to his belt. He toggled the switch on the handset twice, one long, one short.

  ‘Get me on their regimental command net,’ Traxel ordered without breaking stride, his boots ringing on the steel stairs.

  ‘Tempestor, aye.’ Akraatumo scanned through the frequency list on his vambrace. ‘Three-Hundred-and-Seventeenth regimental command net up.’

  ‘Any station on vox, this is First Eradicant. We are inside the fortress,’ Traxel called.

  ‘First Eradicant, this is Cinder Zero,’ one of Mawr’s battalion commanders announced. ‘We’re in pretty rough shape, but comms came up the same time the turrets went inoperative. Colonel Mawr is down and Major Drossa is dead, but we’ve got that Astartes bastard in our sights! We’re hitting him with mortar fire, but he’s still up.’

  ‘Understood,’ Traxel said, as Durlo and Bissot forced the plasteel security doors. ‘We are entering ground level of the main complex.’

  ‘Heads up, First Eradicant,’ the officer said. ‘I think he heard you. He – the Space Marine – has disengaged and is heading your way.’

  ‘I confirm, Cinder. See if you can soften him up.’

  ‘With pleasure.’

  Las-fire sizzled through the doors, perforating the steel and stitching across Durlo’s and Bissot’s carapace. The Scions went low, ducking beneath the fusillade that speared through the door and left fingers of daylight spilling into the darkness.

  ‘Get that door open!’ Traxel ordered.

  Durlo and Bissot shouldered forward into the hatch, las-bolts pelting from their armour as they ineffectually battered at it.

  ‘Move,’ Fennech said. Sparks of white-hot energy crackled across his power fist as he wound up, driving the massive gauntlet into the lock mechanism. The security door exploded from its hinges with the force of a bomb, flattening the black-armoured volley gunner who had been raking it from the other side.

  Fennech’s bolt pistol barked, its deadly payload of mass-reactive shells cracking across the chest and head of the nearest Stygian. ‘Forward, Scions of the Imperium! Forward! In the God-Emperor’s name, let none survive!’

  The security door was situated in the rearmost corner of a broad, open atrium that held the Foretrak Gap facility’s original main entrance. The ceiling-high walls of stained glass in all the windows and main doors had been blown inwards by mortar fire, carpeting the graven basalt of the lobby’s floor in glinting shards. Any furniture that might have once occupied the space had been removed, leaving the chamber wide open and devoid of cover – a double-edged sword, as the five Stygians who defended the room discovered.

  The Scions bounded through the bottleneck at the security door and into the atrium beyond as the wrathful commissar drew the bulk of the Stygians’ fire. Clearing the door, they instinctively peeled off in two teams. The leftmost team, with Durlo at the head, moved along the atrium’s far wall, while Bissot led the other team right.

  ‘Pincer!’ the Stygians’ sergeant warned from her position behind where the volley gunner struggled to his feet. Her hotshot laspistol blazed, striking Durlo in the left shoulder and spinning the Scion into the wall. ‘Split fire!’

  Fist sparking, the commissar leapt towards the reeling Stygian he had fired upon, a shower of las-fire sparking from his cara­pace and refractor field. He swung his crackling, outsized fist in an uppercut that struck the man in the sternum, lifting him into the air as his upper body detonated in a shower of blood, viscera and shattered carapace. The Stygian’s legs continued upwards, striking the ceiling before dropping to the tiles in a bloody, disarticulated heap.

  The atrium’s Stygian defenders responded in good order, going low to present a reduced profile as they exchanged hotshot las-fire with the Tempestus Scions. The volley gunner rolled into a prone position, knocking Phed down as he and another gunner raked fire across Bissot’s team. The Stygian sergeant engaged the second team of Scions, supported by a trooper with a vox-unit on his back.

  Despite their discipline, the odds were stacked decisively against the Stygians. Devoid of cover, the volume of fire from the Scions was overwhelming. Salvoes of highly charged las-bolts chewed inexorably through the defenders’ black plate. Against the far wall, Rybak’s plasma gun discharged with a howl and a whooshing thump, its searing projectile catching the nearest enemy trooper in the centre of his chest, obliterating his entire midsection in a rush of pink mist. In less than half a minute, the atrium’s defenders lay still, cut down by the deadly crossfire.

  A brooding silence settled over the atrium, a stillness so absolute that even the mortar fire outside seemed to cease. Traxel rose to his feet, taking stock of the fallen enemy and the injuries to his own squad.

  He had no sooner risen than a stream of tracer fire, shot rapidly enough to appear a solid beam, raked the atrium, punctuated by the tumult of massed heavy bolter fire. A heavy bolter round struck Quisse beneath the sternum, nearly cutting him in half as his carapace ruptured, while the stream of solid shot caught Phed in the side as he rose and tore out through his abdomen. Shrapnel spanged from the Scions’ armour as a mortar round exploded just outside, kicking up a cloud of dust.

  The lord of the fortress entered the chamber, his massive boots of iron and ceramite crunching on shattered glass as he racked his enormous rotary-barrelled chaingun. He thumbed the power button atop the trigger grip, setting the weapon’s barrels spinning with a high-pitched whine.

  IX

  Blodt strode from the dust cloud, untroubled by the mortar barrage following in his wake. Smoke belched from the barrels of his Reaper chaincannon as his armour’s automated hoppers cycled the ammunition in the drumlike magazines on his back. Sunlight flashed on the black-and-yellow hazard stripes embellishing his plastron, right pauldron and left greave. Scratches shone brightly on the dull iron casing and aged brass edging of his ancient war plate, where shrapnel had scoured it down to grey ceramite beneath its skin of metal. The augmetic scope which covered nearly the entire right hemisphere of his battle helm’s domed crown glowed an infernal red through the settling dust.

  The massive warrior was flanked by four servitors, their right arms replaced by smoking heavy bolters. They had been heavily modified, their bodies plated with thick slabs of iron which had been bolted directly to their augmented skeletons. Their heads were likewise encased in iron, targeting optics glowing balefully from stylised skull masks resembling the badge the Iron Warrior wore on the sable field of his left shoulder. They held their fire, waiting with lobotomised patience as their master reloaded.

  Blodt had been listening to the loyalists’ transmissions since they breached the western cordon, marking each so that he knew them by name and function, even if he did not yet know what they were. The green-armoured Imperial troopers fled before him, scrambling to reach the stairwell they had only recently left as his chain­cannon’s spinning barrels vomited fire. One pitched headlong down the stairs in an uncontrolled spin, bowling over two others as a high-velocity round struck his backpack.

  ‘Fall back to the central control facility!’ their leader shouted, sprinting down the stairs. He pulled two of the fallen to their feet as a volley gunner dragged their medicae forward and down the passageway.

  The eradicant, so he had heard them call themselves, fled – the gunners formed a rearguard as they made for the level’s centre­most chamber. They cleaved to the walls as they ran, keeping themselves out of the open centre of the corridor.