‘The scouts report a dozen villages and towns further west of here,’ Jebe replied after glancing at Yusuf. ‘If he has passed through, someone will remember an armed group and an old man. We will drive him onwards, further and further from his cities. He cannot run for ever.’

‘He has managed this far,’ Tsubodai snapped. He turned to Yusuf, who still stood there, shifting his weight from foot to foot. ‘You did well, Yusuf. Now leave us.’

The young man bowed deeply. It was a good thing they paid well, these Mongols. If the shah could evade them until winter came again, Yusuf would be a rich man. As he walked back through the camp, he nodded and smiled to some of the warriors he knew. They were quiet as the evening came, as wolves were quiet when there was no prey in range. He saw them sharpening their swords and repairing arrows, slow and steady in their work. Yusuf shuddered delicately. He had heard of the attack on their women and children. He would not like to see what happened when they finally caught the shah and his sons.

Jelaudin rubbed his eyes, furious at his own weakness. He could not let his three brothers see his air of confidence fade, not when they looked to him every day with fear and hope.

He winced in the darkness at his father’s labouring breath, in and out in a slow wheeze that seemed to go on for ever. Every time it ceased, Jelaudin listened in despair, not knowing what he would do if the silence stretched and stretched around him.

The Mongols had brought the old man down, just as if they had struck him with one of their shafts. The pursuit across plains and mountains had never allowed the shah to rest and recover. Damp ground and torrential rain had meant they all suffered colds and aching joints. At more than sixty years of age, the old man was like a bull, but the damp had seeped into his lungs and torn the strength right out of him. Jelaudin could feel tears spring fresh to his eyes and he rubbed them too hard, digging the heels of his hands into the sockets so that the pain would ease his anger.

He had never been hunted before. In the first month, it was like a game to him. He and his brothers had laughed at the Mongols on their trail, coming up with ridiculous plans to lose them. As the rains had come, they had laid false trails, split their force, then split it again. They had ordered men to their deaths in ambushes that barely seemed to slow the implacable enemy who streamed after them.

Jelaudin listened as his father’s breath crackled in the dark. His lungs were full of thick muck and he would wake soon, choking on it. Jelaudin would pound him on the back as he had so many times before, until the old man’s skin lost its waxy look and he could rise for one more day on the run.

‘Curse them all to hell,’ Jelaudin whispered. The Mongols must have had men who could follow the path of a bird in flight. Four times Jelaudin had risked turning his father back to the south. On each occasion, they had seen a distant line of scouts, spread wide and watching for just such an attempt. On the last, they had been forced to run to exhaustion, finally losing themselves in a city market. Jelaudin had barely escaped with his life and his father’s coughing had started two nights later, after sleeping on wet ground.

It had hurt the brothers to send the last guards away. It was just too easy to track large groups of men, or even the last few dozen who had stayed doggedly with the shah they had pledged to serve. Now only Jelaudin remained with his three younger brothers to tend their father. They had changed their clothes and horses too many times to recall. They had only a little gold left for food and supplies, and when that was gone, Jelaudin truly did not know what would happen. He touched a small pouch of gems, hidden under his robe, taking comfort from the glassy click as he rolled them against each other. Away from the moneylenders in the great cities, he was not sure how he could sell even one safely. It was infuriating. He and his brothers could not live off the land the way the Mongols could. He had been born to silk, with servants to answer his slightest whim.

His father choked in the gloom and Jelaudin reached to him, helping him sit up. He could not remember the name of the small town where they had stopped. Perhaps the Mongols were riding into the outskirts even as the shah heaved for breath.

Jelaudin shook his head, despairing. One more night on the ground would have killed his father, he was sure of it. If it was Allah’s will that they be taken that night, at least it would be in dry clothes, with a meal inside their shrunken bellies. Better that than to have the wolves fall on them as they slept in fields like lambs.

‘My son?’ his father called, his voice querulous.

Jelaudin pressed a cool hand to his father’s forehead, almost recoiling from the heat there. A fever was raging through him and he was not certain the old man even knew him.

‘Shh, father. You will wake the stable boys here. We are safe for the night.’

His father tried to say something else, but a coughing fit broke the words into meaningless bursts of sound. The shah leaned over the edge of the bed to hawk and spit weakly into the bucket. Jelaudin grimaced at the sound. Dawn was close and he had not slept; could not sleep with his father needing him.

The Caspian Sea was more than a hundred miles west of that shabby little town in the middle of moonlit fields. Jelaudin had never travelled beyond it. He could hardly imagine the lands or the people there, but he would be hiding among them if the Mongol line continued to sweep them further and further from home. He and his brothers were desperate to break through those who herded them, but how could it be done? He had even left three men hidden under wet leaves, so that the Mongols would pass them by. If they had survived, they would have brought help as winter came, surely? Every noise in the night was terrifying to the shah and his sons and there were no smiles any more at the enemy who would not stop, would not ever stop until they ran them into the ground.

Shah Ala-ud-Din Mohammed sank back exhausted onto the straw pallet Jelaudin had found for him. His sons would sleep in the filthy stable and still it was better than anything they had known for months. Jelaudin listened to his father’s breathing become quieter and silently cursed the old man for his illness. They seemed to travel a shorter distance each day and Jelaudin doubted the Mongols moved as slowly.

As his father slept, Jelaudin considered going to ground, as he had all through the hot months. He had needed the horses while there was a chance of breaking through, but if they sold or killed the animals and entered a city as a group of travellers, how could the Mongols ever find them? They were only men, for all the fiendish skill of their trackers. He had urged the shah to stop at the ancient slave city of Almashan, but the old man would not hear of hiding like beggars. The very idea seemed to wound him. It had been hard enough to stop his father announcing their presence to the city elders and defying the Mongols from the walls.

To stop was to die, Jelaudin was certain of it. The army chasing his father brought terror with them and few cities would sacrifice their own families for the shah and his sons. The moment the Mongols surrounded a city, Jelaudin knew he would be handed over, or murdered in his sleep. He had few choices left. Jelaudin stared through the darkness at the man who had given orders all his life. It was a hard thing to accept that the shah was too frail to know best how to avoid the animals on their trail. Though Jelaudin was the oldest son, he did not feel ready to scorn his father’s will.

‘We will stop, father,’ he whispered suddenly. ‘We will hide the horses and ourselves in a town. We have enough money to live simply while you recover your strength. They will pass us by. Let them be blind, Allah. If it is your will, let them pass us by.’