Jelaudin came to himself with a start, realising he had not spoken for a long time, instead swaying as he stood in silence.

‘Will your father not object, Nawaz?’ he said at last. ‘I have heard he does not follow the great faith.’ He watched as the prince’s face twisted in dislike.

‘He does not understand, with his thousand shrines and foolish temples. He has forbidden me to go with you, but he has no power over me! These lands are mine and all the wealth of them I give to you. My men are sworn to me alone and my father cannot take them from me. Let me call you master and walk beside you on the road.’

Jelaudin smiled tiredly, feeling the younger man’s enthusiasm ease some of the ache in his bones.

‘Very well, Nawaz. You will lead your men to a holy war and throw back the infidel. You will stand on my right hand and we will triumph.’

Genghis smiled to see his grandson Mongke paddling at the lake edge. His scouts had found the body of water some hundreds of miles to the north-east of Samarkand and he had brought the gers and families there, while his army administered the lands and cities of Khwarezm. The caravans moved again, from as far as Russia and Chin lands, but now they were met by Mongol officials trained by Temuge and backed by warriors. A part of every merchant’s cargo was removed, but in return they needed no guards of their own. The khan’s word protected the roads for a thousand miles and more in any direction from Samarkand.

Mountains surrounded the lake and plain, far enough away that Genghis did not feel enclosed. He knew his warriors would be watching on every peak, but he could not see them. It was somehow comforting to know that the mountains would still be there when all those who lived were dust.

Ogedai had taken well to his new position as heir. Genghis had sent him out with the tumans, learning every detail of the men he would command. That was expected, but Genghis had also placed Ogedai with Temuge, who taught him how to keep an army fed and clothed. Ogedai soaked up every skill the tribes could impart, as well as languages and even writing. The heir was never seen without a group of tutors at his back, but he seemed to thrive on it.

Genghis stretched his back, feeling at peace. The sounds of war were distant in that place and he was enjoying the cries and laughter of the boys in the water, sunning themselves and learning to swim like fish. Some even dived below the surface, launching from rocks in great splashes. Their mothers called and peered anxiously into the depths, but they always surfaced, blowing and laughing at those who worried for them.

Genghis felt a small hand tugging at his leggings and he reached down to swing Kublai into the air. The tiny little boy was only three years old, but from the age of just a few months, he had beamed whenever he saw his grandfather. Genghis had taken a liking to him.

With a jerk, the khan put his grandson on his shoulders and walked to the water’s edge, wincing a little as Kublai gripped his hair too tightly.

‘I will not let you fall, little man,’ Genghis said. He saw Mongke catch sight of the rare treat and hold his arms out to be lifted up in turn. Genghis shook his head. ‘In a while. Until then, Kublai rides.’

‘Another story!’ Kublai called from above his head.

Genghis thought for a time. Kublai’s mother had said his tales were too violent for a little boy, but Kublai seemed to enjoy them regardless. Genghis could see Sorhatani watching him from a little way off down the shore. At nineteen years old, she had grown into a woman of unusual beauty. Genghis sometimes wondered how little Tolui had snared her.

‘Would you like to hear about the khan of the Assassins?’

‘Yes, tell me!’ Kublai shouted joyfully.

Genghis smiled, turning this way and that so that the boy giggled at the sudden movements.

‘He was a huge man,’ Genghis said, ‘with arms strong enough to bend an iron bar. His beard was like black wire and it stretched almost to his waist! It was two years ago that I came across him in his fortress. He leapt on my back as I passed underneath an arch and I could not break his grip. I felt his hands around my throat, squeezing and squeezing until I thought my eyes would pop out from my head!’

He mimed a terrible grip, while Mongke came out from the water and watched with his eyes wide.

‘How did you get him off?’ Mongke asked.

Genghis looked down and thought for a moment.

‘I could not, Mongke. I tried to shake him free, as I am doing with Kublai here, but he was too strong for me. He squeezed even harder and suddenly I saw my eyes rolling on the ground in front of me.’

‘How could you see them if they were on the ground?’ Kublai asked immediately.

Genghis laughed and lifted him down.

‘You are a clever boy, Kublai, but you are right. I could not see them. In fact, I could see me, with just holes where my eyes used to be and the Assassin still clinging to my back. Yet as my eyes rolled, I saw a great ruby flashing in his forehead. I did not know it was his weakness, but I was desperate. With my hands, I reached up and ripped it out. His strength went with it, for the gem was the source of all his power. I collected my eyes and sold the ruby to buy a white horse. I survived, but even today I have to be careful that my eyes do not come out again when I sneeze.’

‘That is not true,’ Mongke said scornfully.

‘It is,’ Kublai said, determined to defend his grandfather.

The khan chuckled.

‘Who can say if I have remembered every detail correctly? He may not have had a beard.’

Mongke snorted and struck his leg, which Genghis did not seem to notice. When Kublai and Mongke looked up, they saw their grandfather gazing into the distance, where two men were riding across the pebble beach towards him. A change came over the khan at the sight and both boys watched quizzically, not understanding why the light mood had come to an end.

‘Go to your mother now. I will tell you another story tonight, if I have time.’

Genghis did not watch them as they pelted away, sending sand and pebbles skittering from their bare feet. Instead, he straightened fully to receive the scouts. He knew the men who rode to him. He had sent them away from the families more than a year before, with carefully worded orders. Their return meant they had either failed, or found his missing son. He could not tell from their faces as they reached him and dismounted, bowing deeply.

‘My lord khan,’ the first said.

Genghis had no patience for polite greetings.

‘Did you find him?’ he snapped.

The man nodded, swallowing nervousness.

‘In the far north, lord. We did not stop to check once we saw gers and ponies of the sort we know. It could not be anyone else.’

‘Gers? He took none with him,’ Genghis replied. ‘He has made a home then, so far away from the memory of me. Did his men see you?’

Both scouts shook their heads with utter certainty, remaining silent. The khan would not want to know the details of how they had crept close to Jochi’s rough settlement, hiding themselves in snow though they almost froze to death.

‘Good,’ Genghis replied. ‘You have done well. Take six fresh horses from my herd as your reward: two mares, two stallions and two of the younger geldings. I will commend you to your general for this work.’

The scouts bowed again, flushed with success as they mounted and rode to the maze of gers along the banks of the lake. Genghis was left alone for a moment, looking out over the waters. In all his life, not one of his generals had refused an order, or even considered betraying him. Not until Jochi had vanished, taking seven thousand valuable warriors with him. Genghis had sent scouts in all directions, searching lands new and old for his son. It had taken almost two years, but he had found him at last. Genghis shook his head as his thoughts grew dark. It would end in blood, after all he had done in raising another man’s son as his own. The entire nation spoke of the vanished army, though not in the presence of the khan. Jochi had given him no choice.