'It's the Grand Mountain, isn't it?' asked Kuyper, using the Titan drivers' old name for Olympus Mons. The moderati of Victorix Magna twisted in the reclined couch at the Warlord's chin mount to face Cavalerio. 'She frets about something.'

'The Grand Mountain,' agreed Cavalerio. 'She speaks with the voice of Mars and something troubles her.'

'My princeps!' called Sensori Palus. 'Vox contact from Ascraeus Mons. Princeps Sharaq urgently requests to speak with you.'

'On the Manifold,' ordered Cavalerio.

A ghostly hash of green light swam into focus before the reclining princeps, a holographic image of Princeps Sharaq standing in the Chamber of the First. The image jittered like a jammed signal, the words fading in and out as though the code was somehow corrupt.

'What is it, Sharaq?' demanded Cavalerio. 'We are on-mission.'

'I know, Stormlord, but you must return to Ascraeus Mons immediately.'

'Return? Why?'

Sharaq's answer was blotted out by a squealing blurt of code like an animalistic bellow of rage, his image distorting as if in the grip of a rippling heat haze.

'…Mortis. They march!'

'What? Repeat last,' snapped Cavalerio.

Sharaq's image suddenly sharpened, and Cavalerio heard the next words as clearly as if his fellow princeps had been standing before him.

'Legio Mortis,' repeated Sharaq. 'Their engines walk. And they are heading towards Ascraeus Mons.'

Dalia stared in fascination at Ipluvien Maximal, wondering how much of him was mechanical and how much was human. From the little she could see of his body beneath the coolant robes he wore to preserve the integrity of the machine parts of his body, the answer was not much. There was precious little left of the magos that spoke of their shared racial kinship.

'You have never seen an adept of the Mechanicum like me?' asked Maximal.

'No,' said Dalia. 'Most of the ones I've seen still look human. You sound human, but you don't look it.'

Maximal turned to Adept Zeth and blurted a crackling burst of code, the viewscreens attached to his host of mechadendrites flashing with his amusement.

'Oh, I'm sorry,' said Dalia. 'I didn't mean to speak out of turn, I was just curious.'

The robed magos turned back to her. 'You understand binaric code? Without modifications?'

'I've picked it up,' said Dalia, embarrassed at the scrutiny.

Maximal nodded his oblong, helmeted head, the whirring lenses adjusting to better view Dalia. 'You were right, Zeth, she is quite remarkable. Perhaps this project of yours might actually bear fruit after all.'

Dalia looked past the hulking form of Maximal to the wide window that looked out into the domed chamber where Jonas Milus was strapped to the theta-wave enhancer, beneath the sightless eyes of the thousands of psykers encased in the coffers of the dome.

'It will work, I'm sure of it,' whispered Dalia.

'Let us hope so, young Dalia,' said Maximal. 'A great deal depends upon it.'

'You have a lovely voice,' said Dalia. 'It's rich, like a well-spoken man of the Romanii. Why would you bother with a voice like that when you look like you do?'

'We all have our foibles, Dalia,' explained Maximal. 'This voice belonged to a great singer of operatic verse and the sounds remind me of all that is good in mankind.'

Dalia didn't know what to say to that, so returned her attention to the view beyond the armoured glass that was all that separated the control room from what was about to happen.

An army of calculus-logi attended to a bewildering bank of cogitators and logic engines that controlled aspects of the Akashic reader she had not known about. Many of the symbols on the panels were unknown to her or used words she didn't know. The control room was a thrumming box of tension and activity, the sense of something great and portentous heavy on everyone's features.

Even the servitors looked tense, though Dalia told herself that it was just her imagination.

'When does it start?' asked Dalia, turning to her colleagues.

Caxton and Severine shrugged and even Mellicin had no answer.

'It starts now, Dalia,' said Adept Zeth appearing at her side and placing a bronze gauntlet on her shoulder. 'All of this is down to you.'

'Then let's just hope it works,' said Dalia, looking at the distant, serene features of Jonas Milus.

'Terran horizon clear,' said an automated voice. 'Astronomican light readings approaching test window parameters. Alignment on track.'

'Removing pentobarbital wards from psychic foci,' said the toneless voice of a calculus-logi. 'Increasing aperture of pineal antenna.'

'Magma generators diverting power to collectors.'

'What do all those things mean?' asked Dalia.

'You remember I told you that it takes a great deal of energy to breach the walls separating us from the aether?' said Zeth.

'Yes.'

'Well, it takes a form and amount of energy that cannot be generated here on Mars.'

'What kind of energy?'

'Psychic energy,' said Zeth, 'in quantities that can only be harvested from one source, the Astronomican.'

'The Emperor's warp beacon? The one that guides starships?'

'The very same,' said Zeth, pointing towards the metallic disc at the dome's apex, from which golden spears of energy were arcing. 'Only the Astronomican has the required psychic energy that will allow the Akashic reader to access the sum of all knowledge we seek. We will divert a fraction of its power into the chamber to empower the psykers and open the gates to the aether.'

'Won't it disrupt the Astronomican if we use its power?' asked Dalia.

Zeth looked over at Maximal, a moment's hesitation giving Dalia the answer she sought.

'It will,' admitted Zeth, 'but only for a short span of time.'

Dalia stepped towards the consoles that operated the Akashic reader, assimilating what Zeth had just told her into her understanding of what was being said and what the words carved into the wooden panels meant.

She had no real idea of how powerful the Astronomican was, but understood that even a fraction of its energy would be greater than anything she could imagine. She looked into the chamber at the waking psykers and knew with sudden, awful, clarity that she had overlooked something.

'How are you going to divert the Astronomican's power?' she asked.

'Mars will be in alignment with Terra soon and we will pass through the radiance of the psychic beacon. The pineal antennae will collect the energy and divert it to the psykers.'

'Is that how you've always done it?' asked Dalia urgently.

Adept Zeth shook her head. 'No. This will be the first time we have passed through the Astronomican.'

'Oh no,' whispered Dalia. 'The calculations are wrong. They're all wrong!'

'Wrong, what are you talking about?' demanded Adept Maximal.

'The energy readings,' said Dalia. 'I understand now… the different readings. Fluctuating maximums and minimums. Apogee and perigee… That's why the numbers were different. We assumed a baseline average, but that's not what we're going to get now.'

'Dalia, explain yourself,' said Zeth. 'Talk me through your concerns.'

'The raw data you gave us to work with…' said Dalia. 'I based the upper levels of assumed energy transference on the psychic strengths you've used so far, but this time the energy levels will be hundreds… thousands of times greater than before. The reader used fragments of reflected and refracted psychic bleed… scraps and trickles of psychic energy, but this is going to be a raging torrent!'

'Psychic confluence in five, four…'

'Adept Zeth,' said Dalia, tearing her eyes from Jonas Milus and spinning to face the Mistress of the Magma City. 'We have to stop this. It's going to be too much!'

'Don't be ridiculous,' said Zeth. 'We cannot stop it.'