Ogedai rubbed his eyes for a moment, feeling the dizziness clear. He could not tell them that he expected Chagatai to be khan after him. Only the spirits knew how long he had left, but he had built his city. He had left a mark on the plains and he would be khan. In darkness, Ogedai awoke. He was sweating in the warm night and he turned over in bed, feeling his wife stir beside him. He was drifting back into sleep when he heard a rattle of running footsteps in the distance. He came alert instantly, raising his head and listening until his neck ached. Who would be running at such an hour – some servant? He closed his eyes again and then heard a faint knock at the outer door of his rooms. Ogedai swore softly and shook his wife by the shoulder.

'Get dressed, Torogene. Something is happening.' In recent days, Huran had begun the habit of sleeping outside the rooms, with his back to the outer door. The officer knew better than to disturb his master without good reason.

The knock sounded again as Ogedai belted a deel robe. He closed the double door on his wife and crossed the outer room, padding barefoot past the Chin tables and couches. There was no moon above the city and the rooms were dark. It was easy to imagine assassins in every shadow and Ogedai lifted a sword from where it hung on the wall. In silence, he removed the scabbard and listened at the door.

Somewhere far away, he heard a distant scream and he jerked back.

'Huran?' he said. Through the heavy oak, he heard the relief in the man's voice.

'My lord, it is safe to open the door,' Huran said.

Ogedai threw back a heavy bolt and lifted an iron bar that anchored the door to the stone wall. In his nervous state, he had not noticed that the corridor cast no threads of light through the cracks. It was darker out there than in his rooms, where dim starlight gleamed through the windows.

Huran came in quickly, stepping past Ogedai to check the rooms. Behind him, Tolui ushered in Sorhatani and his two eldest sons, wrapped in light robes over their sleeping clothes.

'What is happening here?' Ogedai hissed, using anger to cover his spreading panic.

'The guards on our door went away,' Tolui said grimly. 'If I hadn't heard them leave, I don't know what would have happened.'

Ogedai tightened his grip on the sword, taking comfort from the weight of it. He turned at a spill of light from the inner doorway, his wife silhouetted against the lamplight.

'Be still, Torogene, I will attend to this,' he said. To his irritation, she came out anyway, her night robe clutched around her.

'I went to the nearest guardroom,' Tolui went on. He glanced at his sons, who stood watching in open-mouthed excitement. 'They were all dead, brother.'

Huran grimaced as he peered out into the dark corridors.

'I hate to lock us in, my lord, but this is the strongest door in the palace. You will be safe here tonight.'

Ogedai was torn between outrage and caution. He knew every stone of the vast building around them. He had watched each one cut and shaped and polished and fitted into place. Yet all his halls, all his power and influence, would be reduced to just a few rooms when the door closed.

'Keep it open as long as you can,' he said. Surely there were more of his Guards on their way? How could such an attempt have slipped past him?

Somewhere nearby, they heard more running footsteps, the echoes clattering from all directions. Huran put his shoulder to the door. From the blackness, a figure loomed suddenly and Huran struck with his sword blade, grunting as it slid off scaled armour.

'Put that away, Huran,' a voice came, slipping into the room.

In the dim light, Ogedai breathed in relief. 'Tsubodai! What is happening outside?'

The general said nothing. He dropped his sword on the stone floor and helped Huran bar the door, before taking up the blade once again.

'The corridors are full of men; they're searching every room,' he said. 'If it were not for the fact that they have never been inside your palace before, they would be here already.'

'How did you get past?' Huran demanded.

Tsubodai scowled in angry memory. 'Some of them recognised me, but the common warriors have not yet been told to cut me down. For all they know, I am part of the plot.'

Ogedai sagged as he stared round at the small group who had run to his rooms.

'Where is my son Guyuk?' he said. 'My daughters?'

Tsubodai shook his head. 'I did not see them, lord, but there is every chance they are safe. You are the target tonight, no one else.'

Tolui winced as he understood. He turned to his wife. 'Then I have brought you and my sons to the most dangerous place.'

Sorhatani reached out to touch his cheek.

'Nowhere is safe tonight,' she said softly.

They could all hear voices and running feet coming closer. Outside the city, the tumans of the nation slept on, oblivious to the threat.

Kachiun walked his pony across the churned grass of the encampment, listening to the sounds of the nation all around him. Despite the stillness of the night, he did not ride alone. Thirty of his personal bondsmen went with him, alert for any attack. No one travelled alone in the camps any more, not with the new moon almost upon them. Lamps and mutton fat torches spat and fluttered at every intersection of paths, revealing dark groups of warriors watching him as he passed.

He could hardly believe the current level of suspicion and tension in the camps. At three points, he was challenged by guards as he approached Khasar's ger. In the night breeze, two lamps cast writhing yellow shadows at his feet. Even as Khasar came yawning out onto the cart, Kachiun could see bows drawn and sighted on him.

'We need to talk, brother,' he said.

Khasar stretched, groaning. 'Tonight?'

'Yes, tonight,' Kachiun snapped.

He didn't want to say more, with so many listeners nearby. For once, Khasar sensed his mood and nodded without any more argument. Kachiun watched as his brother whistled softly. Men in full armour walked in from the outer darkness, hands near their swords. They ignored Kachiun and walked to their general, standing close by his feet and looking up at him for orders. Khasar crouched and murmured to them.

Kachiun mastered his impatience until the men bowed their heads and moved away. One of them brought Khasar's current mount, a gelding near black in colour that whickered and kicked out as they saddled it.

'Bring your bondsmen, brother,' Kachiun said to him.

Khasar peered at him in the dim light, seeing the strain in Kachiun's face. He shrugged and gestured to the officers nearby. Another forty warriors trotted to his side, long woken from sleep by the presence of armed men near their master. It seemed that even Khasar was taking no chances on those nights while they waited for the new moon.

Dawn was still hours away, but with the camp in such a state, the movement of so many men woke everyone they passed. Voices called out around them and somewhere a child began wailing. Grim-faced, Kachiun trotted his mount beside his brother, silent as they headed towards Karakorum.

Torches lit the gates in dim gold that night. The walls were pale grey shadows in the darkness, but the western gate gleamed, oak and iron, and clearly shut. Khasar frowned, leaning forward in his saddle to strain his eyes.

'I haven't seen it closed before,' he said over his shoulder. Without thought, he dug in his heels and increased his pace. The warriors around him matched him so smoothly it could have been a battlefield manoeuvre. The noises of the camp, the calling voices, all were lost in the thump of hooves, the breath of horses, the jingle of metal and harness. The western gate of Karakorum grew before them. Khasar could now see ranks of men, facing outwards as if challenging him.