Uriel had seen patterns like that once before, when he had looked through a crystal dome into the seething depths of the warp when the Omphalos Daemonium had seized the Calth's Pride in its grip.

'Welcome, Uriel Ventris,' said the left mouth. 'I am Kulla.'

'And I am Lalla,' said the other.

'We are the Janiceps,' they said in unison.

Lalla's voice was sweet and sounded like a carefree young girl who knew nothing of the cruelties of the world. Kulla's, on the other hand, was bitter and husky, as though she alone bore the full knowledge of what the vagaries of unthinking nature had wrought upon them.

Uriel stared in uncomfortable fascination at the conjoined girls, unsure of what to say.

Astropaths were often eccentric souls, cursed with the ability to hurl their minds across the vastness of the galaxy and communicate with others of their kind, thus allowing the Imperium to function.

Uriel had seen many astropaths, but none as physically tormented as the Janiceps, none so cursed by birth as to be better off dead than consigned to this fate. On ninety-nine worlds out of a hundred, the girls would have been killed, but whichever world had birthed them had obviously been a more tolerant place.

As much as Uriel felt sorry for them, he couldn't shake the sense that they were dangerous mutants and fought to get past that impression.

'Don't feel sorry for us, Uriel,' said Lalla. 'We like being useful.'

'Be quiet,' snapped Kulla. 'What do you know of useful? I do all the work!'

'Come now, girls,' said Barbaden, his voice unusually soft and yielding. 'You shouldn't argue. You know what happens when you argue.'

'Yes,' sulked Kulla. 'You have your damned warders tighten their noose on us.'

'And it hurts us so!' squealed Lalla.

'This is the astropath?' Uriel asked Barbaden.

'You can speak to them yourself,' said the governor, 'they're right in front of you.'

'He thinks we're mutants, Kulla,' said Lalla pleasantly.

'Well, aren't you?' asked Uriel.

'No more than you, Astartes,' sneered Kulla. 'What are you if not a freak? In fact your gene structure is more removed from humanity than ours.'

Uriel took a deep breath. From the precautions Barbaden had taken with their confinement, Kulla and Lalla were obviously powerful psykers and it would be foolish to needlessly antagonise them.

'Yes, it would,' smiled Kulla.

Uriel started and Lalla sniggered. 'She does that all the time, but don't worry, she can only read your surface thoughts, unless you want her to read more, and then we'll know all your sins.'

'I am a Space Marine of the Emperor, I have no sins,' said Uriel.

'Oh, come now,' said Lalla, laughing, 'we all have our secrets.'

'No,' said Uriel, 'we don't.'

'He's got secrets to hide,' said Kulla, laughing with a cackling screech that stretched the membrane across her brain.

'Can we get on with this?' asked Uriel, uncomfortable in the presence of the Janiceps now that he knew they could read minds as well as communicate telepathically with other astropaths.

'Of course,' said Barbaden, amused at Uriel's discomfort. 'Simply kneel before the twins and do as they tell you. It will go much quicker if you do not question everything.'

'Both of us?' asked Pasanius.

'If you'd like to,' said Lalla. 'It wouldn't make any difference.'

'Then I think I'll sit this one out,' said Pasanius, gesturing to Uriel to step up.

'And you have awards for valour,' said Uriel.

'The burden of command is that you sometimes have to lead from the front,' replied Pasanius, 'and she said it wouldn't make a difference.'

'How convenient,' said Uriel, kneeling before the twins.

'Give us your hands,' said Lalla, 'and hold on.'

Uriel nodded, wondering at the necessity of Lalla's last comment, and lifted his hands towards the girls. He took their hands hesitantly, feeling the rapid pulse of blood in their tiny, delicate fingers.

'We're not made of china,' said Kulla. 'I thought you Astartes were supposed to be strong. Grip our hands.'

Lalla giggled and Uriel blushed as he tightened his hold.

'That's better,' said Kulla. 'Now we can control your mind.'

Uriel's eyes widened, but Lalla smiled. 'She's joking. We wouldn't do that, not without asking you first.'

His hands became cold and he felt the chill spread along his arms and into his chest. How much of the twins' banter was playful and how much was truth, he didn't know, but he had the feeling that were they of a mind to do him harm, there would be nothing he could do to prevent them from killing him with a thought.

'So what do I need to do?' asked Uriel, trying not to let his unease show.

'Where are you sending this message?' asked Lalla, her eye drifting shut.

'Who are you sending it to?' demanded Kulla.

'To the Ultramarines,' said Uriel. 'To the world of Macragge.'

'Open your mind, Astartes,' ordered Kulla, her voice rasping and harsh.

Uriel nodded, though the instruction was vague, and closed his eyes, slowing his breathing and awaiting the touch of the twins' mind. He felt nothing and tried not to get impatient.

'Your mind is closed to us,' said Lalla, 'like a fortress preparing to resist an invader.'

'I don't understand,' said Uriel.

'You Astartes, your minds are as rigid and unbending as adamantium,' said Kulla, and Uriel knew that her mouth was not moving. Her voice was arriving directly in his thoughts without recourse to speech. 'You are trained, conditioned and enhanced in so many ways, but your minds are like locked doors to a place of miracles and wonder. All the potential you are trained to access: memory, language, combat analysis, and yet your masters train you to close off the one part of your mind that might actually allow you to soar. You do not feel as others do, but we can open that door for you if you let us.'

'Stop it, Kulla,' said Lalla. 'You know that's not allowed. Leave him to his blindness.'

'Oh, all right,' sulked Kulla, with a sigh that Uriel heard in his mind. 'Very well, Astartes, picture your home world: its people, its mountains and its seas. Smell the earth and taste the air. Feel the grass beneath your feet and the wind on your face. Remember all that makes it what it is.'

Pleased to have an instruction he understood, Uriel pictured his last sight of Macragge, a beautiful blue globe turning slowly in the depths of space. The vast seas that covered much of its surface shone with an azure light and spirals of storm clouds, like miniature galaxies, spun lazily in the atmosphere.

Passing through the clouds, Uriel pictured the awesome marble colossus that was the Fortress of Hera upon the great peninsula. He saw the soaring fluted columns of its majestic portico, the colonnades filled with statues of heroic warriors. His mind soared onwards, over golden roofs, silver domes and towering spires of glittering light: magnificent libraries, halls of battle honours, and gilded halls of pilgrims and worshipers come to the Temple of Correction, where the body of the mighty Roboute Guilliman was held in stasis.

Beyond the Fortress of Hera, Uriel imagined the wild, untamed glories of the Valley of Laponis, its white cliffs towering above the achingly blue river that wound its way through the mountains to the plains below. As though a bird in flight, Uriel plummeted down through the valley, speeding towards a thundering waterfall cascading from the heights above.

Billowing clouds of spray boomed into the air, filling it with bitingly cold mist and Uriel laughed aloud as he tasted the crystal clear waters of his Chapter's home world. He soared from the valley, visualising the mountains and forests of Macragge, the sweeping, rocky coastlines and vast, depthless oceans.