Horus, then? Was it Horus?

Perhaps. Dorn knew that Horus was the greatest of them, which made him the gravest foe. Could any one of them hope to best Lupercal on the field of war?

Martial prowess was hardly the point. Dorn had never feared an adversary in his life because of how strong he was or how hard he fought. Combat was only ever a test.

What mattered, what engendered fear, was why an adversary fought. What made him fight.

Oh, now we have it. Now the truth dawns, he felt the hairs on his skin rise. I'm not afraid of Horus. I'm afraid of finding out why he has turned against us. I cannot conceive of any justification for this schism, but Horus must have his reasons. I am afraid that when I know them, when they are explained to my baffled mind, I might… agree.

'Would you tear them all down?'

Dorn turned at the sound of the voice. For a moment, it had sounded like the soft growl of his father.

But it was just a man, a cloaked and cowled man scarcely half Dorn's height. His robes were those of a simple palace administrator.

'What did you say?' asked Dorn.

The man walked out into the circle of the Investiary to face Dorn. He greeted him with the old salute of Unity rather than the sign of the aquila. 'You were staring at the statues of your kin,' he observed. 'I asked… would you tear them all down?'

'The statues or my kin, Sigillite?' Dorn replied.

'Both. Either.'

'The statues, perhaps. I believe Horus is doing a fine job with the men themselves.'

Malcador smiled and looked up at Dorn. Like Dorn's, his hair was white. Unlike Dorn's, it was long like a mane. Malcador was an exceptional being. He had been with the Emperor from the inception of the Unification Wars, serving as aide, confidant and advisor. He had risen to become the master of the Council of Terra. The Emperor and the primarchs were genetically advantaged post-humans, but Malcador was just a man, and that was what made him exceptional. He stood on a par with the post human masters of the Imperium, and he was just a man. 'Will you walk with me, Rogal Dorn?'

'Are there not matters of state that require your attention, even at this hour, sir? The Council will bemoan your absence from the debating table.'

'The Council can manage for a while without me,' Malcador replied. 'I like to lake the air at this time of night. The Imperium never rests, but at night, up here in the thin air of the old Himalazia, I find there is at least an illusion of rest, a time to think and free the mind. I walk. I close my eyes. The stars do not go out because I am not looking at them.'

'Not yet,' said Dorn.

Malcador laughed. 'No, not yet.'

They said little at first. They left the Investiary and walked along the beige stones of the Precinct's highest terraces, between the weeping fountains. They walked as far as Lion's Gate, onto the platforms that overlooked the docking rings and landing fields of the Brahmaputra Plateau. The Gate had once been a thing of magnificence, two gilded beasts rising up to lock claws in a feral dispute. Dorn's order of works had replaced them with giant grey donjons stippled with casemates and macro gun ports. A curtain wall of bleak rockcrete encircled the gate, its edge fletched with void field vanes like the spines of some prehistoric reptile.

They stood and considered it for a long time.

'I am not a subtle man,' Malcador said, at length.

Dorn raised his eyebrows.

'Oh, all right,' said Malcador, 'perhaps I am. Guile comes easily to a politician. I know I am considered cunning.'

'An old word, with no more meaning than "wise",' Dorn replied.

'Indeed. I will accept that as a compliment. All I meant to say was, I will not attempt to be subtle now.'

'No?'

'The Emperor has expressed his concerns.'

'Meaning?' Dorn asked.

Malcador answered with a slight sigh. 'He understands you are filled with misgivings.'

'Only natural, I would think, given the circumstances,' said Dorn.

The Sigillite nodded. 'He trusts you to undertake the defence. He counts on you. Terra must not fall, no matter what Horus brings. This palace must not fall. If it is to end here, then it must end in our triumph. But he knows, and I know, and you know, that any defence is only as strong as its weakest part: faith, belief, trust.'

'What are you telling me?'

'If there is doubt in your heart, then that is our weakness.'

Dorn looked away. 'My heart is sad because of what I have been made to do to this place. That's all it is.'

'Is it? I don't think so. What are you really afraid of?'

Mai.cador raised his hand and the lights in his chambers came on. Dorn looked around, he had never entered the Sigillite's private apartments before. Ancient images hung on the walls: flaking, fragile things of wood, canvas and decomposing pigments, preserved in thin, blue fields of stasis; the smoke pale portrait of a woman with the most curious smile; garish yellow flowers rendered in thick paint; the unflinching, rheumy gaze of an old fleshy man, cast in shadow, tobacco brown,

Along another wall hung old tattered banners showing the thunderbolt and lightning strike sigil of the Pre-Unity armies. Suits of armour - perfect, glinting thunder armour - were mounted in shimmering suspension zones.

Malcador offered Dorn wine, which he refused, and a seat, which he accepted.

'I have made a certain peace with myself,' Dorn said. 'I understand what I am afraid of.'

Malcador nodded. He had pulled back his cowl and the light shone on his long white hair. He sipped from his glass. 'Enlighten me.'

'I'do not fear anyone. Not Horus, not Fulgrim, none of them. I fear the cause. I fear the root of their enmity.'

'You fear what you don't understand.'

'Exactly. I am at a loss to know what drives the Warmasler and his cohorts. It is an alien thing to me, quite defying translation. A strong defence relies on knowing what you are defending against. I can raise all the bulwarks and curtain walls and cannon-bastions I like, and I still won't know what it is I'm fighting.'

'Perceptive,' said Malcador, 'and true of us all. I fancy even the Emperor doesn't fully understand what it is that drives Horus against us so furiously. Do you know what I think?'

'Tell me.'

Malcador shrugged. 'I believe it is better that we don't know. To understand it would be to understand insanity. Horus is quite mad. Chaos is inside him.'

'You say that as if Chaos is a… thing.'

'It is. Does that surprise you? You've known the warp and seen its corrupting touch, that's Chaos. It has touched humanity now, twisted our brightest and best. All we can do is remain true to ourselves and fend it off, deny it. Trying to understand it is a fool's errand. It would claim us too.'

'I see.'

'Don't see, Rogal Dorn, and you will live longer. All you can do is acknowledge your fear. That's all any of us can do. Recognise it for what it is: your pure, human sanity rocked by the sight of the warp's infecting, suffocating madness.'

'Is this what the Emperor believes?' asked Dorn.

'It's what he knows. It's what he knows he doesn't know. Sometimes, my friend, there is salvation in ignorance.'

Dorn sat still for a while. Malcador watched him, occasionally sipping from his glass.

'Well, I thank you for your time, sir,' said Dorn eventually. 'Your candour too. I should—'

'There is one other thing,' said Malcador, setting his glass down and rising to his feel. 'Something I want to show you.'

Malcador crossed the chamber, and took something from a drawer in an old bureau. He walked back to Dorn, and spread that something out on the low table between them.

Dorn opened his mouth but no sound issued. Fear gripped him.