He opened a channel to his lord and master and said, 'Lord Berossus, the charges beneath the fortress are set and ready to be detonated.'

'Then detonate them now,' came the familiar growling rasp of his master's voice. 'We are almost at the head of the ramp.'

Pausing to savour this moment of his greatest triumph, Keagh allowed the dim silence of the tunnel to enfold him before sending a pulse of energy along the length of the cable.

The mountain itself shook with the force of the blast far below, thousands of tonnes of ordnance and fuel exploding in one simultaneous blast that instantly atomised a whole swathe of the bedrock of Medrengard. Honsou staggered and fell to his knees as the Shockwave rippled throughout the fortress. Tall towers that had stood for millennia crashed down to ruin and every fighting man was knocked from his feet.

Tanks, and even one of Berossus's Titans, tumbled from the ramp as the Shockwave fanned upwards from below. Cracks split the stonework of the battlements and hundreds died as they fell to their deaths upon shattered ramparts. The main wall crumbled, torn like paper and breached in a dozen places by the shear forces twisting the mountain.

Aftershocks continued to rumble, shaking Khalan-Ghol to its foundations and Honsou heard a deep, answering roar, as though the fortress itself cried out in rage at this violation.

His fortress had been breached, but Honsou felt nothing but elation as the growling tremors that gripped his fastness began to fade.

'Now I have you, Berossus!' he snarled. 'Iron Warriors, ready yourselves!'

PART FOUR

THE ENEMY OF MY ENEMY…

CHAPTER EIGHTEEN

Corias Keagh felt the thunderous roar of the explosion force its way down his tunnels like the bellow of an angry god. He braced himself against the wall of his underground bunker, confident that his works would survive this violence he had unleashed. He heard the metal of his tunnel supports groan in protest at the power of the Shockwave, but Keagh had been digging mines and bringing ruin to fortresses from below for thousands of years and knew his craft well.

Only when the temperature readout on his visor leapt upwards did he realise that something was amiss.

He heard it first as a whooshing rush of superheated air, forced through the tunnels ahead of something unimaginably hot. He rushed out into the tunnels as a terrible fear suddenly seized him.

Leaping from tunnel to tunnel, a flashing cloud of incandescent vapours foamed along the length of his workings. Behind it came a roaring, seething orange glow of molten metal and Keagh heard the screams of the soldiers as the lethally hot steam boiled the flesh from their bones.

He knew then that every one of the thousands of men in the tunnels beneath the ramp was going to die. His tunnels had not breached the sepulchres of Khalan-Ghol, but somewhere else entirely.

But how could that be, when the location of Keagh's breaching gallery had come straight from Obax Zakayo…?

In the split second Keagh had left of life, he realised that that they had been horribly deceived - that all they had striven for was ruined.

He turned to run, but even one as enhanced as an Iron Warrior could not outrun millions of tonnes of roaring molten metal as it spilled from the forges of Khalan-Ghol, destroying everything before it and liquefying the earth of the ramp as it went.

Keagh was engulfed in the rushing torrent of fire and had the exquisite horror of a last few seconds of life before his armour was melted away and his flesh vaporised.

Uriel felt the immense power of the subterranean explosion spread through the landscape and stumbled, gripping the sharp rocks of Khalan-Ghol's peak tightly as the tremors shook the foundations of the world itself. Plumes of glowing, orange steam geysered from the foot of the mountain and, as he watched, more and more began bursting from channels cut into the monstrous ramp.

'What in the Emperor's name?' breathed Uriel as he looked up and saw the top of the ramp sag and collapse upon itself as though the weight of earth supporting it was being steadily removed.

'A countermine?' shouted Pasanius.

'It would need to have been colossal to cause such damage,' said Uriel, shaking his head.

'Emperor angry at iron men,' roared the Lord of the Unfleshed. 'Strikes them from heaven!'

'He does indeed,' nodded Uriel, risking a glance at the gory features of the creature and feeling immense relief that Vaanes was not here to see the expression on his own face.

The renegades had turned their backs on them, spitting on this last chance for redemption and had marched away without a single word as soon as they had reached the surface. Uriel had watched them go, his heart heavy at their betrayal of what it meant to be a Space Marine, but relieved that he himself had been tested and not been found wanting.

Truth be told, there was some merit in what Vaanes had said. Perhaps this was a suicide mission and would see them all dead. And perhaps as well there was merit in survival, for where was the glory or honour to be had from their deaths?

But Uriel knew that for a true warrior of the Emperor there was no terror of death, only the fear that he might die with his works unfulfilled.

The death oath placed upon them by Marneus Calgar remained to be honoured and even should they fail in their quest, their deaths would respect the chance their Chapter Master had given them, so long ago it seemed, on Macragge.

As he watched Vaanes and the renegades depart, Uriel knew that though he was probably going to his death, his was the better choice.

'We fight iron men now?' asked the Lord of the Unfleshed. 'Show us way in!'

The primal ferocity in the Lord of the Unfleshed's face reminded Uriel just how precarious their situation was. There was no guarantee that his plan would succeed and he did not want to think of the consequences should the Unfleshed decide that he no longer spoke with the Emperor's voice.

'Soon,' said Uriel, resuming his climb of the rocks that led to the fighting above.

Honsou took the steps from the high spire that led to the main wall quickly, thinking that the swelling roars of hate he could hear were a fine hymn upon which to wage war. He and Onyx and a coterie of his finest warriors emerged onto a cracked series of barbican ramparts, arranged in a saw-toothed pattern, freshly constructed behind the main walls.

Smoke wreathed the breaches and the Khalan-Ghol's main gate hung in splinters, a pack of frenzied dreadnoughts smashing through it. At their head, Honsou saw Lord Berossus, his mechanised arms hurling warriors before him in sprays of blood. A wild, orgiastic howling screeched from his vox-amp and Honsou grinned ferally as he knew that he would not allow Berossus to survive this battle.

Billowing clouds of scalding steam and the crack of splintering stone from beyond the ruined walls told him that the top of the great ramp was no more, the stone and earth running molten and collapsing under the strain of supporting Berossus's armoured column.

Virtually everything metal within the fortress had been smelted down and the forges had burned constantly to ensure that when Berossus's engineers breached the fortress from below - as Honsou had known they would - they would be tunnelling into a great reservoir of molten metal and not the catacombs they expected.

Honsou knew that a warsmith as gullible as Berossus did not deserve to live: his very existence weakened the Iron Warriors. To have believed that Honsou would not have known of Obax Zakayo's treachery and use him against his paymasters was ludicrous, but had proven to be his salvation.