The rear door of the Mammoth transport lowered with a snarl of hydraulics, and a gust of Rychter's hot, dawn air washed a wave of sand into the vehicle's lower bay. The clamps of Ryke's docking cradle unlatched at the same instant the ramp thudded to the badlands earth and he thundered outside, HK-Rupture spreading out behind him in a bristling crescent of metal.

He scanned the area immediately outside the Mammoth for hostile targets, the Hunter-Killer's sensors snapping aggressively at the slightest flicker of movement. Indicators winked up on the HUD before turning blue as the machine confirmed the fast-moving forms of Scout Cadre skiffs, and the low, angular hulls of Captain Brendle's tanks.

They spread out, toothed metal feet ripping into the badlands earth as they powered away from the looming bulk of the Mammoth. So far he saw no surprises; no signs of their new enemy. He wondered how sensitive the Crawlers were to seismic activity – whether or not they were already aware of the human force on some level, like spiders sensing vibrations in a web.

He guessed that they would find out soon enough.

"Lockjaw – Caesar," he called. "All clear."

"Copy. All Hunter-Killer squadrons proceed with deployment," Harcourt grunted back.

Just as their meticulous battle plan dictated, the other Hunter-Killers came thundering from the belly of the Mammoth in an ever expanding front. Charpente's mechs came out next, their aquamarine armour dulled from weeks of frontline combat, closely followed by the rust brown brutes of HK-Bandit. The northern contingent followed them; HK-Gladiai, decked out in regal red, but he could see signs of battle – scorches and scratches on the normally shining paintwork. These pilots had seen at least some active combat.

HK-Ferocci, Colonel Harcourt's personal guard, came last. Their Hunter-Killers were heavier than the standard variants, bulkier and gleaming crimson in the rising light. He saw no signs of combat on them, but that didn't detract from their imposing appearance as they thumped out across the plain. Harcourt's mech itself was a Riot pattern, with a crescent-shaped shoulder shield and a long, spike of a cannon slung under the opposite arm. Two of their number dragged a large, armoured cradle along behind them on thick, balloon wheels. Its spherical, armoured casing was three meters across, and contained the enormously powerful mine they would be deploying. Too large to be fired from a launcher, this one would be delivered the old fashioned way.

"Caesar – SC21," Harcourt rumbled. "Status update."

"Scout teams deployed to the tunnels," Brackenshaw replied. "Expect visual confirmation of targets within three minutes."

"Understood. All squadrons move to your pre-assigned staging areas. AC-12, take up bombardment positions. Sergeant Mattise, deploy bridging teams at your discretion."

He watched it all unfold on the HUD, even as he piloted his own mech into position with expert ease. The Hunter-Killers wove through the Scout Cadre cordon while the armoured escort vehicles grumbled away to hunker down in the dunes, heavy cannons overlooking the warren, ready to reduce the place to rubble at one word from Harcourt. The bridging teams – part of Mattise's Engineering Cadre detachment – rode in a trio of skiffs, hurtling into the open warren with their cargo of heavy ramps that would be deployed to allow the Hunter-Killers access into the labyrinth of tunnels dug by the Crawlers.

First in line, HK-Rupture followed them in, with Harcourt's squad close behind. Charpente and the other two squads moved to the eastern network of the tunnels to strike the nest from multiple angles at once. Ideally that part of the strike force could draw the attention of enough of the Crawlers to allow Ryke and his troops to smash a hole to allow Harcourt's people to deploy the mine.

They had just reached their staging areas when the call came from Brackenshaw. The advance scouts on their speedy, single person skiffs had confirmed what they all knew. The Crawlers were still down there. Hundreds of them. Ryke watched with a small stab of envy as the trio of intrepid scouts that had braved the depths came racing out of the tunnel in front of them, buzzing like gnats.

"Lucky for some, eh?" Brigg joked as they sped away.

"Miss your breakfast today, Avalanche?" Thaye chided. "This is what the Hunter-Killers are for. Who else is going to do the dirty work?"

"I think you enjoy this job a little too much."

"Gotta love what you do."

"Drown the chatter, folks," Ryke muttered. "Lockjaw – Caesar, we are ready to proceed."

"All units," Harcourt declared on the wide-band in response, his tone imperious. "We have visual confirmation of our targets. All Hunter-Killers, begin your descent."

Acknowledgements cascaded over the comm and a low clang echoed through the warren as the engineers that had accompanied them deployed their ramp. The thing was a broad slab of black metal with toothed hooks at one end that sank deep into the lip of the hole they would be descending down, providing the Hunter-Killers with their way in. He could have jumped into the black pit – the mech's formidable shock absorbers could handle the landing – but jumping back out again would have been impossible. Specced for brawling with Scraegans, getting a Hunter-Killer off the ground had not been much of a consideration in their design.

The ramp boomed into place and Ryke flicked HUD of his Hunter-Killer to its dark-display.

"HK-Rupture, on my lead," he ordered quietly. "We're going to be single file down there so make sure you keep your combat spacing. If we find a party on our way down, watch what you shoot at."

"Hope nobody's afraid of the dark," Kim muttered.

"Or claustrophobic," Preese laughed. "And I thought Scraegans had bad taste in digs. What do you think boss?"

Ryke smiled thinly as he trudged down the ramp into the gloom. "I think they lack a bit of imagination. Now come on."

They marched down into the darkness, the Hunter-Killers fitting into the passages without much room to spare. He'd known the dimensions – the report by Kelso and Brackenshaw had been thorough – but now that he was down here he shuddered to think about fighting in such close proximity. Even in the underground warrens of the Scraegans there had been space to manoeuvre. Here it would just be a kill-or-be-killed brawl if their approach was discovered.

Their contingent moved on, following the directions Brackenshaw had provided with the bomb carrying duo bringing up the rear with their precious cargo. Blackness closed in around them but the high-powered optics of his mech cut through it, giving him a blue-laced display of the passage ahead. Proximity counters clicked away on the HUD, the indicators of his squad spread behind him in a long straggled line that looked achingly vulnerable.

Reports came through from HK-Bandit. The other arm of the attack force were making good progress, approaching the central chamber fast from the east. Ryke was thankful for the inbuilt map that had been loaded into their Hunter-Killer systems from Brackenshaw's sortie. The thought of navigating this place by eye made his skin crawl. Minutes ticked by; their target location loomed larger and larger – a blob of red that beckoned them deeper.

It took twenty minutes for them to make their way through the tunnel to their destination. He found himself softening his steps as much as he could – though a fifteen ton war machine could only be so quiet. The passage began to broaden out as they closed in and Ryke felt his heart beginning to beat faster. He remembered his first encounter with these things vividly, and time had not sweetened it. He remembered how tough the creature had been, and suddenly found himself wondering if fifty Hunter-Killers could really be enough to pull this off.

Too late to turn back now though.

Moving with painstaking care, he led the others out to the edge of the cavern.

They filtered out behind him in two long ranks, and the Hunter-Killer display gave him a frighteningly detailed look at just what they were facing down here. The floor of the chamber was carpeted with huge, knobbly forms, and the machine picked out more than a hundred individual shapes with just a cursory pass through. Towards the centre of the mass he could see the bulbous, totem-like blocks of what looked like eggs. The real target for their mission. In reality it was a little over a hundred meters away but that felt awfully far right now.

"By the Riverlords," Carpenter murmured, her voice barely more than a whisper. "There are a lot of them out there."

"Just means more of them will be heading to the River tonight," he assured her, keeping his voice firm. "Lockjaw – Torch, we are in position."

"Copy that, Lockjaw. We are moving into firing positions now."

He glanced to his left, to the tunnels where the rest of their attack force began to emerge from, tricking out like great drops of metal water. One by one they slid into place, cannons swivelling to target the mass of Crawlers that lay clumped in an ungainly, tangled mass between them and their target.

A moment later all fifty Hunter-Killers had made it into the chamber, spread along the north eastern edge of tunnels in a broad arc looking inwards. An eerie quiet settled over them and Ryke could feel sweat beading on his forehead. The Crawlers seemed to be asleep. Small shifts of movement were picked up on the HUD and his audio filters could detect a strange, bellow-like huffing of breath. A faint mist hung over the creatures, thick with carbon dioxide.

It was almost peaceful.

Then heads started to turn. A baleful hissing began to fill the air and long limbs extended from the dark. The whole floor of the cavern seemed to come alive, and begin sliding towards them.

"All units, deploy flares!" Harcourt barked.

"Copy that." Ryke exhaled hard, flexed his neck from side to side, and triggered the flare release.

It was like a hundred glowing serpents suddenly went blazing out into the cavern. Single-use disposable launchers blossomed in the darkness, sending dozens upon dozens of flares searing out across the air from the entire northern half of the chamber. The ranks of Hunter-Killers were briefly visible, weapons bristling in the light of the salvo.

Then the flares exploded amongst the sea of arthropod bodies.

Hissing rose in a violent cacophony as the creatures reacted to the sudden light. Huge armoured forms smashed into each other with bone-breaking force. Gut wrenching cracks echoed loudly as limbs snapped under crushing weight, and in the space of a moment the whole seething mass fell into complete chaos.

"Caesar – Torch," Harcourt shouted to the officer commanding HK-Bandit. "Engage at will."

The man didn't reply over the comm, his response coming instead in a murderous salvo of fire that tore into the reeling creatures. Those closest to the Hunter-Killer ranks were riddled with armour piercing rounds, many of them flailing under the shock of the flares and exposing their undersides to the fire. Conventional mines arced overhead, descending and digging through – and on more than one occasion lodging in – the bodies of their foes before detonating.

Crawlers further away from the attack began moving. The mass of their bodies shifted position, jaws clacking and venomous hissing filling the air as blocks of them began to recognise the threat. As they began shifting towards the thirty Hunter-Killers at the eastern edge, Harcourt gave the command.

"On your lead, Lockjaw. Make me a path, if you please."

Ryke smirked. "Yes, sir." He switched to his squadwide and stepped forward, his cannon thrumming with readiness. "You heard the colonel, ladies and gentlemen. Let's make some space. Fire at will!"

A fresh salvo erupted from the flank of the Crawlers that had turned to face Charpente and the others. HK-Rupture and the members of HK-Ferocci not currently dragging their payload let rip and more arthropods went down, limbs shattered as the Hunter-Killers deliberately aimed away from their armoured carapaces. Ryke took a step forward. And another. His cannon shook with recoil as he clung on, pumping a steady stream of shells into the mass of bodies. Confusion reigned in the ranks of the enemy and the thick, wall of arthropod armour began to splinter as they tried to decide which threat to approach first.

Ryke knew it was now or never. The moment of indecision would not last long. They had a brief window to cut right to the heart of the chamber.

"On my lead!" he roared, still firing as he charged.

In a wedge, the members of HK-Rupture followed him into the crush. He sprinted full tilt at the closest creature that was still failing around awkwardly with half its legs smashed to splinters, and rammed a shoulder into its head.

Twisting his body, he shunted the creature off balance and out of his way, sending it crashing into one of its fellows and sending a burst of cannon fire after it for good measure. Thaye hurtled past him with her warblade unsheathed, ducking the snap of another Crawler's jaws and hacking at one of its legs. The limb was ripped off at the joint by the savage force behind the blow and the monster pitched forward with a screeching snarl of pain.

They had the element of surprise and they used it. HK-Rupture led the charge with controlled brutality, driving deep into the heart of the Crawler nest, hacking, blasting, shoving and smashing as hard as they could. Brigg and Brody utilised their shoulder cannons at virtually point blank range to clear a path, while the Raptor mechs piloted by Kim and Ricardo danced their way through the melee, slicing at legs to cripple as many of the beasts as they could.

But the Crawlers only stayed surprised for so long.

The scream that crashed over the comm made Ryke spin around to find Marlowe Carpenter's mech getting borne forward with one Crawler on her back. The things huge limbs curled around her, crushing the Hunter-Killer against its grinding, under-maw. Mech and monster crashed to the ground, and the arthropod's forty ton mass pinned her to the ground.

"Covering!" Qadira yelled, racing into the fray and hammering her warblade into the Crawler's snapping head. She leaned the full weight of her Hunter-Killer into the strike and there was a splintering crunch as the double jaw split apart, sending gouts of grey blood splattering in all directions. Her blade went down its throat, along with her hand.

She let out a bellow of effort and wrenched free again. The Crawler slumped dead on top of its victim.

"Marlowe!" Ryke shouted. "Talk to me."

"My back, my back," Carpenter whimpered.

"Give me some cover!" he roared, lunging back over and slamming his whole body into another beast as it tried to rise. Brody thundered into view, using the power and weight of his Goliath mech to heave the creature's bulk off of Marlowe's mech. Once it was out of the way, Ryke could only stare in horror at the damage.

The back armour of the mech had been simply torn to pieces. Coolant systems bled out onto the ground and he could see dozens of vital shredded wires sparking and cracking. The mech wasn't going anywhere.

That meant neither was the pilot.

"Everflowing," he cursed, trying to think of a way out, but their situation had not gone unnoticed. Three more Crawlers were scuttling towards the stricken mech. He turned his gun on them; Brody's cannon boomed vengefully.

"Ryke, I... I can't feel my legs," Carpenter coughed over the comm.

"Hang tight," he said through gritted teeth. "Help's on the way."

"Vannigan!" Harcourt bellowed. "We need a path cleared now! Stay on mission, soldier."

"Sir?!"

"Damn your eyes, Sergeant, remember why we came here."

Pure rage rose up in Ryke's mind. If Harcourt had been in front of him he would have killed the man there and then. He twisted aside as one of the Crawler's lunged at him, breaking one of its forelegs with a swing of his shoulder shield. Brody shot it in the face as it reeled back, sending it crashing to the ground, mortally wounded.

"On my lead!" Harcourt roared. "For Rubicon! And Rychter!"

"Colonel – sir!" Ryke blurted, spinning around to see Harcourt thundering off at the head of his squadron, right into the teeth of the Crawler line. The beasts had converged on their position after slowing down the forward drive of HK-Rupture, and now the northern colonel had just made himself a prime target.

That might not have bothered Ryke so much, if the bomb hadn't gone with him.

"Hatchet, Medea, Mallet, stay here," he barked, swivelling away from Marlowe's stricken mech, still with no idea how he could help the girl trapped and wounded in its wreckage. "The rest of you, on me!"

Anger coursed through him as he raced off in pursuit of Harcourt, his eyes fixed on the heavy cradle of the atomic mine. If they lost that, none of this would matter. The gleaming crimson mechs of HK-Ferocci went crashing into a wall of armoured bodies, cannons spitting fire in all directions, blades hacking as they pressed forward.

The momentum of their advance died quickly, thwarted by the thickening mass of Crawler bodies blocking their path. More of their enemies came closing around from the sides, as if sensing the threat of the bomb, and Ryke hurled himself forward to try and prevent Harcourt's troops from being surrounded. On the other side of the cavern their comrades were starting to push forward as the creatures that had been attacking them began to melt away, but none of the other Hunter-Killers were close enough to help them right now.

Ryke buried his warblade into the underside of one Crawler, twisting and yanking his mech around in a wild zig-zag motion that opened the monster's underside, dumping its sludgy grey blood all over him. He shook himself violently to clear the much from his optics, stumbling clear as the beast fell. Kim lost her shoulder shield in the underside mouth of one Crawler that tried to land on her from above. Damage indicators were climbing on the mechs of his force.

Marlowe Carpenter's Hunter-Killer showed an inert crimson mass. By the standards of the HUD, she was already dead.

Try as they might, they couldn't catch up to Harcourt. It took too much time, ammo and force to even wound the arthropods enough to take them out of the fight. More and more of the things piled in around the beleaguered HK-Ferocci. One of the pilots guarding the bomb disappeared as one creature exploded from the ground beneath him and hauled his thrashing mech down into a shallow hole.

The second Hunter-Killer shoved the bomb clear of the pit but was instantly grappling with another Crawler that came lunging out of the gloom. Two of the Rubicon pilots were dead already and Ryke saw Harcourt in the middle of three of the things, flailing and blasting at them.

"All units! Press on!" he bellowed. "Converge on my position. The mine-,"

He didn't finish. One of the Crawlers smashed into him from the side and send the colonel's bulky mech crashing to the ground. Swearing, Ryke rammed his foot down on the head of a stricken creature and propelled himself up and over its writhing bulk, trying to get to Harcourt. Another Crawler swept its whip-like tail at him and he had to stop, turning to ride the blow on his shield.

Thaye rammed it from the side, buckling three of its legs with her shoulder shield held crossways across the body of her mech. It collapsed, hissing in anger as she leapt on it, stabbing for all she was worth.

She bought Ryke just enough time to look up and see two more arthropods slam down onto Harcourt's Hunter-Killer, legs punching through its front armour, jaws latching onto armour plates and pulling savagely. There was a half-scream followed by tearing, rending crack that made bile rise in Ryke's throat.

He could do nothing but watch as the Crawlers ripped Harcourt's mech in half, and the colonel along with it.