Ryke led his squad down the shallow slop of a rocky dune, the feet of his Hunter-Killer dislodging miniature avalanches with each step. They moved at battle-pace, hooking down and around a towering outcrop of blackened stone and out into the gently sloped gully that the scouts had marked out.

The skiffs commanded by Boxley and Kalashnik emerged from their hiding place about a hundred yards ahead, sliding from the shadows between a pair of dunes. The two blade-like craft traversed, engines flaring as they slid into formation, flanking the charging Hunter-Killers.

"Just over the next rise," Boxley radioed. "You'll be in weapons range as soon as you clear it, so go in hot."

"Copy that. When we're engaged, sweep behind us to catch any stragglers," he replied before switching to the squad-wide band. "You heard the man. Weapons free as soon as you have a target – don't wait for my command."

The other pilots fired off their acknowledgements crisply as the mechs mounted the base of the slope. Pistons snarled as they propelled the war machines upward, gouging divots in the ground with every step. Ryke could feel his heart thundering, adrenaline rushing into his system as combat beckoned. A step in front of the others, he cleared the top of the rise and looked down.

Even at a glance, what he saw was very strange.

The base of the dune levelled out into another cluster of snaggle-toothed crags, but the signs of battle were everywhere. The whole place was torn up, the scorch marks of furnace cannon blasts in evidence all around, and several of the rocky outcrops had been smashed to their foundations. Strange, bulbous mounds of pulverised rocks dotted the valley floor, and the Hunter-Killer's keen optics picked out more of the strange whip-marks gouged into the terrain.

Stranger still: there were dead Scraegans, five that he could count so far, their shaggy forms motionless and devoid of heat. A dozen more of the beasts shambled around the outcrops, some slouching as though wounded.

What in the Everflowing happened here?

Was he looking at some kind of Scraegan infighting? From this distance it was impossible to tell how the beasts had met their demise. The other warriors were moving away, however, not waiting to claim their dead. Ryke didn't know a whole lot about Scraegan culture – nobody did – but it had been widely documented that Scraegan packs didn't leave their members behind.

Something in their motions didn't look right. There was a skittishness he'd never seen before. The Scraegans didn't fear anything, but right now they scattered like a pack of startled sand-dogs.

The time for examination came quickly to an end, however, as the Scraegans spotted the Hunter-Killers stampeding down the slope towards them. A stocky, boulder-chested Beta reared up, barking a warning to the remaining pack members as it pivoted, furnace cannon glowing. The others responded frantically, guttural roars echoing up to meet Ryke's force.

They replied with a crushing salvo of fire. Their guns spun into life, spraying streams of armour-piercing shells down towards the Scraegan line. Booms resonated from just behind him as the Goliath pilots opened up, the thunder of their heavy weapons rolling deafeningly out across the valley.

Blue bolts of furnace cannon fire ripped up the rise towards them in a sporadic volley, gouging into the slopes and vaporising furrows of earth. The well-drilled mechs under Ryke's command split apart to avoid the fire, and in amongst the tangle of crags the two sides crashed together.

"Combat pairings!" Ryke roared as he and Thaye closed together. The pilots followed suite and a melee erupted all around him.

Scraegan bodies thrashed past him, clubs and axes swinging wildly, close range furnace blasts scorching metal and rock. He took a blow on his shield; shoulder charged the attacker and pivoted sideways to get his back to Thaye. She leapt forward, thick warblade glinting in the half-light as she attacked.

The first Scraegan she met took a gouging slice to its upper arm before spinning away with a howl of pain. She jerked diagonally past it to ram her shoulder shield into a second. Ryke swept along in her wake, making sure no enemies tried to flank her. A glance at the HUD showed him a spread out skirmish, but something seemed off. Something about this seemed less brutal than he was used to.

Then he realised that some Scraegans had already burst clear in the initial charge, but rather than coming back into the fight, they simply kept going, moving out of the crags towards the open desert to the south.

His mind spun in confusion. He'd never seen a Scraegan back down from a fair fight, but here and now they seemed to lack the stomach for it.

Some of them, at least. As he and Thaye plunged into the thick of the Scraegan line, Ryke found himself face to face with the stocky warrior commanding the enemy force. The beast was smaller than most Betas he'd seen, but no less fearsome for it, its granite-coloured fur sheathed in slabs of scarred armour plating, its skull plate surmounted by a serrated metal horn. It bellowed in challenge even as other Scraegans blundered past it.

"Lockjaw, left flank!"

The warning cry from Koral burst over the comm. He reacted with the speed of trust.

The furnace cannon shot snarled overhead as he wrenched himself to one side, missing him by a matter of inches. It screamed up and past, and slammed into the overhanging spur of black rock directly above him. The Hunter-Killer's auditory filters picked out the ominous crunch of breaking stone and he looked up.

Then he swore and dove forward into a crashing roll, leaving a slab of rock the size of a house to pulverise the ground he'd been standing on an instant before. The Beta was on him as he rose, the pair slamming together with ground-ripping force, and he twisted violently to one side, trying to fling the charging creature past him.

Ryke managed to avoid getting clamped in its grip, but as he corkscrewed away the warrior lashed out with its hammer, its bodyweight wrenching it into a full 360 degree spin. The hammer caught him in the shoulder with a deafening clang of metal-on-metal. Amber warnings blurted over the affected area.

Gritting his teeth, he reset his feet, cannon spinning into life and spitting shots at the Scraegan. A few shots found their mark, but the beast didn't come back at him, instead rolling over several times, its momentum carrying it until it twisted to its feet in a motion of jarring gracefulness. It turned back long enough lash a furnace cannon shot vaguely in Ryke's direction, but it seemed clear. The warrior was suddenly running away.

Struggling to process such a thing, Ryke looked around and to his amazement he saw that the rest of their enemies were now doing the same. Hunter-Killers shot and stabbed at them as they charged, but it quickly became clear these Scraegans didn't want to fight. They engaged for only as long as they needed to break through the human line, racing for the safety of the open ground where they could burrow.

The Beta bellowed commands to the Scraegans still entangled in the brawl, and those few soon dragged themselves clear. One went down, its body pierced by dozens of shells, but the others couldn't be stopped. Ryke looked across the line of the skirmish and saw two more dead Scraegans claimed by the guns and blades of his squad.

The survivors thundered away, with the Beta urging them on. It walked backwards, furnace cannon glowing as it covered the escape of its comrades. Soon the bulk of the pack cleared the crags, plunging their massive bodies down into the loose earth beyond. Fountains of muck and grit burst skyward as they twisted themselves like living drills, disappearing underground with armour piercing rounds snapping at their heels. Ryke stumped to a halt, letting his cannon drop and staring at the ground in bafflement.

"Hold your fire," he ordered, bemused. "Stand down."

Silence fizzed on the comms as the Hunter-Killers eased down their combat posture, indecision descending on them. He stared as the Beta vanished into the ground, leaving only a thick smear of disturbed earth behind. The wrongness of it all set him on edge more than any battle. The Scraegans didn't give up, certainly not in a fight of even numbers. Ryke watched on his HUD's short range seismics as the pack reading disappeared south, moving fast and far. They were fleeing like the River itself was about to come crashing down on them.

"Boss?" Preese said eventually. "What in the Everflowing is going on around here?"

He shook his head. "Drowned if I know."

"Did that really just happen?" Thaye murmured, and he could almost feel her discomfort spilling over the comm link. "Ryke, they just... ran off."

"Sergeant," Qadira cut in stiffly. "I think we should take a closer look at the bodies. They don't look right."

"We're going to take a closer look at everything here," Ryke agreed. "Pair off, make sure your cams are recording properly. Document every inch of this valley. Boxley, Kalashnik, bring your flights in. If you've got any volunteers, we should get up close to these bodies for some samples."

"I'll see who I can bribe," Boxley replied. "On our way."

Ryke shook his head within the confines of his Hunter-Killer, powering down the weapons systems and double checking his camera feeds were still active. The displays flickered on his HUD – one camera stud on the right side had been dislodged by the impact of the Scraegan hammer, but otherwise he had a full suite.

With Thaye stomping along behind him, he turned his mech around and walked down into crag-infested valley, to where the other Scraegan bodies lay. Up close, he could see the claw-like rips in the rock, almost identical to the ones they'd discovered on their way here. All around him the strange markings marred the landscape, and he could see large bowls of shattered stone in the ground. It looked similar to what the Scraegans left behind when they dug, but they didn't tunnel into solid rock.

Not as far as he knew, at any rate.

Ryke let his cameras linger on the markings for a few seconds before turning away and approaching the first Scraegan corpse. As soon as he took a closer look at it he knew something was very wrong here. The Scraegan lay face down, and an almost perfect circle of gore two meters across filled the space that had once been its broad, armoured back. He swallowed, fighting down the nausea.

"Pissing Rivers," Thaye muttered. "Looks like someone took a coring drill to this poor bastard."

Ryke nodded, making sure his camera angle could fit the whole spectacle. It wasn't a furnace cannon impact, that much was clear. The wound wasn't cauterized; no signs of burns or blasts. The rest of the Scraegan's body seemed largely unharmed.

Reports soon came through from the other Hunter-Killers and the Scout Cadre troops. The other Scraegans were in much the same condition, their bodies torn up by what looked like some kind of industrial drill. No-one had any notion as to what might have caused it. He wondered if the Scraegans had some kind of new weapon, and some disagreement had led them to turn it on each other. But that didn't explain the flight of the pack that had been here. Why had they run? What were they trying to hide?

"Lockjaw, standby," Boxley called over the comm. "I'm going to take a closer look at one of these things."

Ryke looked up and saw Boxley's skiff hovering alongside another body a few dozen yards away. He watched as four figures rappelled deftly down from the vehicle, landing on the battered ground and unslinging rifles as they turned to the Scraegan.

Seconds ticked by as they circled the body, getting close enough to touch it. Some conversation between the scouts that he couldn't hear took place, the soldiers gesturing to one and other. After a moment, one man handed his rifle to another and clambered awkwardly up onto the corpse. He edged gingerly along the dead Scraegan's huge frame before dropping to his haunches, examining the cavernous wound in the beast's chest.

Then the scout's posture seemed to change. He leaned in close; cocked his head quizzically to one side. Then, to Ryke's surprise, he reached forward, down into the wound. The soldier tugged at something for a few seconds, but Ryke was too far away to see exactly what it was. Then with a jerking suddenness, he tore the object loose. Ryke saw a flash of white and crimson.

"Err, Lockjaw?" Boxley said uneasily. "I think you might want to take a look at this."

"What is it?"

"Well, I'm no biologist," the scout replied. "But whatever it is, I just pulled it out of this thing's ribcage."

More confused than ever, Ryke trudged over to the scouts. As he reached them, Boxley hopped down from the Scraegan body, cradling something large in his arms. The Scout Sergeant walked around the corpse and up to Ryke, holding the mystery object high for closer inspection.

Ryke focused his cameras and his eyes went wide with astonishment. The thing was the length of a human torso, slightly curved and tapering to a sharp point. Barbs ran the length of one side and at the broad end it seemed to swell, with strange, gangly tendrils hanging off it it. Beneath the oily black smears of Scraegan blood he could see the unmistakable shine of bone-white. His blood ran cold when he realised just what he was looking at.

It was a tooth. A gigantic tooth.