Rho-mu 31 placed his stave against the wall, and once more the side of the vessel became opaque. The hull began to vibrate and screech as they descended through the blistering thermals.

'Do they ever have crashes here?' asked Dalia, knowing that such accidents could have no survivors. 'I mean, have any ships gone into the lava?'

'Sometimes,' said Rho-mu 31. 'It is best not to think of it.'

'Too late,' muttered Dalia, as the noises of the ship's engines changed in pitch from a low rumble to a high-pitched shriek, attitude thrusters firing to correct the rip tide air currents. The pilot was clearly having difficulty in lowering their ship to the landing platform, and Dalia closed her eyes, trying not to think of what would happen if they went into the lava.

She tried not to picture the lava searing the meat from her bones, the fumes choking her and the agonising pain of watching her body disintegrate in front of her. Of course she would not live long enough to experience these things, but her mind delighted in tormenting her with these dreadful visions of catastrophe.

Dalia took a deep breath and forced the images from her mind, fighting to keep them from overwhelming her. She felt a thump on the underside of the craft and her eyes flashed open.

'What was that? Has something gone wrong?'

Rho-mu 31 looked at her strangely, and though the bronze mask concealed his features, Dalia could sense his amusement at her panic.

'No,' he said. 'We have simply landed.'

Dalia let out a shuddering sigh of relief, pathetically grateful to be on terra firma once again… though should that more properly be mars firma? Having said that, how solid could the ground be considered when it was somehow supported on an ocean of liquid rock that could burn her to cinders in the blink of an eye?

A hiss of escaping gases drew her attention to the ramp at the rear of the vessel as it began to lower with a squeal of pistons. A wall of hot air rushed to fill the compartment and Dalia gasped at the sudden heat. Sweat immediately prickled on her brow and her mouth dried of saliva in an instant.

'Throne alive, it's hot!' she said.

'Be thankful for the heat exchangers and gas separators,' said Rho-mu 31. 'You would be overcome by the temperature and fumes of this place in moments without them.'

Dalia nodded, following Rho-mu 31 from the interior of the starship. The other members of his squad moved in behind her as she made her way down the ramp, shielding her eyes from the vivid glare of the lava lagoon and the brightness of the rust-coloured sky. After a day or so in the belly of a starship, she realised how starved of the sight of the sky she had been. Even as a scribe in the bowels of the Librarium Technologica, she had been able to see a sliver of sky through the high liturgical windows.

The sky here was low and threatening, the air thick and heavy with particulate matter billowing upwards from flame-wreathed refineries in the far distance. Though she knew the clouds gathering in the distance were not those of weather patterns, but pollution, she could not help but shiver to see them squatting on the horizon like a quiescent threat.

High railings surrounded the landing platform, and tall silver poles topped with buzzing, hissing machinery punctuated the barrier every few metres - the heat exchangers and gas separators Rho-mu 31 had spoken of, she presumed. A swirling cloud of steam surrounded each one, and dripping pipes ran the length of each pole, vanishing into the decking of the platform to dissipate their heat elsewhere.

'It must take vast amounts of energy to disperse such huge quantities of heat,' she said, pointing at the machines on the silver poles. 'What method do you use to filter the harmful gases from the air? Synthetic membranes, adsorption, or cryogenic distillation?'

'You know of such things?' asked Rho-mu 31.

'Well, I've read about them,' explained Dalia. 'A number of the old texts from the ruins in the Merican deserts mentioned them and, as with everything I read…'

'It slotted home in the archive of your memory as a fact to be recovered at a later date.'

'I guess so,' said Dalia, faintly embarrassed by the reverent tone she heard in his voice.

She looked away from him as she saw an ochre-skinned vehicle emerge from the nearest structure, a tall tower of black metal, and make its way along the boom towards them. It moved on a number of thin, stilt-like legs, moving with a quirky, mechanical gait, like a stubby centipede. As it drew nearer, she saw the wide-bodied mass of a servitor fused and hard-wired into the front section where one might otherwise expect a driver to sit.

The vehicle came to a halt beside them, the multitude of legs twisting it around on its central axis and lowering it to the deck plates.

Rho-mu 31 opened a door in the side of the vehicle and indicated that Dalia should climb aboard. She stepped onto the centipede vehicle and took a seat on the metal bench along its side, feeling a thrill travel through her at the thought of making a journey on such an outlandish mode of transport.

Rho-mu 31 joined her, but the remaining Mechanicum Protectors did not board.

'Where are we going?' asked Dalia, as the vehicle rose up onto its legs once again and set off with a scuttling, side-to-side motion towards the dark tower.

'We are going to see Adept Zeth,' said Rho-mu 31. 'She is most anxious to meet you.'

'Me? Why? I don't understand, what does she want with me?'

'Enough questions, Dalia Cythera,' cautioned Rho-mu 31, not unkindly. 'Adept Zeth does nothing without purpose and you are here to serve that purpose. What manner your service will take is for her to decide.'

The walking vehicle drew near the tower of black metal, and as Dalia looked back towards the gathering clouds, a sliver of fear wormed its way past her wonder at all the new and incredible sights.

She had been brought to Mars with a purpose in mind, but what might that purpose be and would she live to regret the journey?

The shadow of the tower swallowed her, and Dalia shivered despite the awful heat.

Maven's first warning was the transformer exploding in a cascade of flames and whipping electrical discharge. A hammering volley of laser fire, like a hundred lightning bolts ripping from the rocks, sawed through the looped coils of metal and liquefied them in an instant. His display dimmed to protect him from blindness, but before the transformer blew, he saw the outline of the aggressor.

Easily as huge as Equitos Bellum, it was spherical and heavily armoured, a pair of monstrous weapon arms at its sides and a myriad of flexible, metallic tentacles crouched over its shoulders like scorpions' tails.

A trio of convex blisters glowed like baleful eyes on its front, a fiery yellow glow burning from them with a hateful, dead light. The white heat of the explosion obscured the unknown attacker, and by the time the glow had diminished and the Knight's auto-senses had recovered, the war machine had vanished.

With a thought, Equitos Bellum was on a war footing, weapon generators firing from idle to active, and the high-energy cells that drove his Knight switching to battle mode. He immediately stepped his Knight to one side, crouching low as he saw scores of figures pouring from the rocks with weapons raised.

His eyes narrowed as he recognised them as Protector squads, servants of the adepts of Mars. Things were really getting out of hand.

'Stator! Cronus! Are you getting this?'

'Affirmative,' barked Stator. 'Engage enemy forces at will— We will be with you directly.'

'Enemy forces?' hissed Maven. 'They're Protectors!'

'And they are attacking a facility we are duty bound to protect. Now fight!'

Maven cursed under his breath and shrugged, the huge bulk of Equitos Bellum attempting to match the gesture as he marched the machine into battle. He leaned forward in his command seat, lifting his arms and twisting his head as he sought out the enemy war machine.