The two Space Marines edged backwards to the sanctuary of the defile, killing the shrieking, swooping beasts every time they came near. Though they killed dozens of them, Uriel could see hundreds more gathering around the mountaintops and knew that unless they found cover soon, they were as good as dead. They could not hope to hold off that many forever.

The defile was behind them and Uriel glanced along its length as it wound further and deeper into the mountain. Flocks of the delirium spectres circled lower and Uriel prayed they would not be able to follow them.

'I can't tell where it leads!' he said.

'It doesn't matter, does it?' replied Pasanius, bleeding from a patchwork of shallow cuts across the side of his head. 'We don't have much choice.'

'Give them one more blast, then follow me in!'

Pasanius nodded and shouted, 'Go!' and sent another stream of blazing liquid towards the shrieking monsters. Uriel darted into the defile, the narrow basalt walls glassy, black and reflective. It scraped against his shoulder guards, cutting grooves through the paint, and Uriel offered a whispered prayer of forgiveness to the armour's battle-spirit at such careless treatment.

Pasanius backed into the narrow defile, having to force his way sidelong through its narrow length and Uriel had a sickening vision of the pair of them trapped here and waiting to be picked off by these vile creatures.

'Damn, but it's tight,' grunted Pasanius stoically.

Frustrated screeches rang from above and Uriel saw scores of the monstrous beasts flashing overhead across the narrow strip of sky at the top of the defile. He pushed further along its twisting length, the ground sloping upwards and the distance between them and the open sky diminishing with every step.

'We're running out of room!' he called back, as a desperate scrabbling of claws and clanging of metal on stone sounded from above. Hissing beasts, fleshy wings thrashing, forced themselves down into the defile, their screeches echoing deafeningly in the enclosed space. Wails of frantic hunger and longing spat from their bodies and Uriel stabbed upwards, skewering the first of the delirium spectres on his blade.

More forced themselves into the defile, clanging and beating against one another as they struggled to reach their prey.

Unable to fire his flamer in such a confined space, Pasanius ripped them apart with his bare hands, tearing the skin from the desecrated frames with angry bellows. Uriel stabbed and cut blindly, dead flesh enfolding him and sharp teeth snapping at his face. The sound of tearing skin mingled with their grunts of pain and the incongruous noise of joyful souls escaping their hideous torment as each beast died.

'Keep going!' shouted Pasanius in a lull between the ferocious attacks.

'I don't know what's ahead,' answered Uriel.

'It can't be any worse than this!'

Uriel couldn't disagree and forged onwards, wiping clotted blood from his forehead and desperately seeking somewhere that would offer better shelter. The delirium spectres resumed their circling above the defile, patiently waiting for another chance to attack.

The defile twisted and turned, each step winding further into the mountain until at last it turned downwards and led out onto a narrow path that ran along the side of a sheer cliff.

The rockface fell away for hundreds of metres on one side of the path and at its end Uriel could see a narrow cave, its entrance surrounded with a forest of long iron spikes hammered into the rock.

'There's a cave ahead,' said Uriel. 'Looks like someone has used it to hide from these things already.'

'How can you tell?'

'There are spikes around the cave mouth. I doubt these beasts could get near the entrance without fouling their wings.'

'That just begs the question—'

'Who put them there?' finished Uriel.

Pasanius looked towards the sky, hearing the delirium spectres clanging from the rock and their shrill cries drawing closer as they circled down to attack once again.

'We will have to make a break for it,' said Uriel.

'We'll never make it,' pointed out Pasanius. 'They'd be on us before we got halfway.'

'You think I don't know that?' snapped Uriel. 'But we have to try.'

Uriel bit his lip as he wondered how far they could get before the creatures caught them. They might be able to fight some of them off, but not all of them, and even if the monsters didn't kill them, it would be only too easy for them to hurl them from the path.

And to fall such a distance would be fatal, even to one as mighty as a Space Marine.

One of the monsters flew overhead, its blind hunger loathsome and utterly alien.

'Wait…' said Uriel as a memory struggled to the surface of his mind.

'What?'

'When the Omphalos Daemonium spoke of these creatures it said something about how they hunted, something about our hearts and how we wouldn't go unnoticed for long.'

'And?'

'And that's how they are hunting us, they can hear our heartbeats,' said Uriel.

Pasanius was silent for a moment before saying, 'Then we take away what they need to hunt us.'

'You still remember the mantras that trigger the sus-an membrane?'

'Aye, though it's been decades since I've needed to recite them.'

'I know, but we damn well better get them right,' said Uriel. 'I don't want to fall into a coma halfway along that path.'

Pasanius nodded in understanding as Uriel slowly crept to the edge of the defile. The delirium spectres were high above them, but still too close for them to have any hope of reaching the cave entrance unmolested.

Uriel turned to Pasanius and said, 'Go when I go. Slowly, but not too slowly, I don't want you dying on the way.'

'I'll try not to,' replied Pasanius dryly.

Uriel closed his eyes and recited the verses taught to him by Apothecary Selenus that began the hormonal activation of the sus-an membrane, an organ implanted within his brain tissue during his transformation into a Space Marine. He took deep breaths, regulating his breathing and forcing his heart rate to slow. What he was doing was extremely dangerous, normally requiring many hours of meditation and the correct prayers, but Uriel knew they didn't have time for such preparations.

Uriel could feel his hearts pounding in his chest, their rhythmic beats slowing.

Forty beats a minute, thirty, twenty, ten…

He could hear Pasanius repeating the same mantras, knowing that they had to move and reach the cave before the organ activated fully and plunged them into a state, of complete suspended animation and their hearts stopped beating completely.

Three beats a minute… two…

Uriel stood, his vision greying at the edges and his limbs feeling leaden.

He nodded to Pasanius and walked from the transient cover of the defile, moving as quickly as he dared along the path towards the cave mouth. Pasanius followed, the piercing shrieks of the daemonic furies above him almost breaking his concentration and icy sweat streaking his pale face. Both Space Marines hugged the cliff face as they inched their way along the path.

The winged beasts swooped towards them, their shrieks ringing from the cliff-face as they circled and climbed in confusion, unable to pinpoint them.

They were almost at the cave as the flocks above wheeled aimlessly in the air.

Two of the delirium spectres flapped noisily past Uriel, their wings flaring as they landed with a scrape of claws on the path before him. Their cries were low and hideous as they turned slowly their rippling, fleshy skins trying to discern their quarry.

Uriel slowed as he inched his way past the monsters, fighting to hold his body in the limbo between life and a self-induced coma.

He stumbled, his boot scraping against the nearest beast's claws…