Rumours began to fly about the city like bats, sucking the light out of the day. The Manchurian barbarians had conquered Yunnan, Mongolia, Cham, Tibet, Annam and the eastern extensions of the Mughal empire; every day it was somewhere different, somewhere closer. There was no way to confirm any of these assertions, and indeed they were often denied, either by direct contradiction, or simply by the fact that caravans kept coming from some of those regions, and the traders had seen nothing unusual, though they too had heard rumours. Nothing was certain but that there was turmoil to the east. The caravans certainly came less often, and included not only traders but whole families, Muslim or Jewish or Hindu, driven out by fear of the new dynasty, called the Qing. Centuries old foreign settlements dissipated like frost in the sun, and the exiles streamed west with the idea things would be better in Dar al Islam, under the Mughals or the Ottomans or in the taifa sultanates of Frengistan. No doubt true, as Islam was lawful; but Bahram saw the misery on their faces, the destitution and fear, the need for their men to angle and beg for provisions, their goods for trade already depleted, and all the wide western half of the world still before them to be traversed.

At least it would be the Muslim half of the world. But visits to the caravanserai, once one of Bahram's favourite parts of the day, now left him anxious and fearful, as intent as Nadir to see Khalid and Iwang come up with ways to defend the khanate from invasion.

' It's not us slowing things down,' Khalid said bitterly, late one night in his study. 'Nadir himself is no great general, and his influence over the Khan is shaky, and getting shakier. And the Khan himself ' He blew through his lips.

Bahram sighed. No one could contradict it. Sayyed Abdul Aziz was not a wise man.

'We need something both deadly and spectacular,' Khalid said. 'Something both for the Khan and for the Manchu.' Bahram left him looking at various recipes for explosives, and made the long cold ride back to the palace in Bokhara.

Khalid arranged a meeting with Nadir, and came back muttering that if all went well with the demonstration he had proposed, Nadir would release Esmerine and the children back to the compound. Bahram was elated, but Khalid warned him: 'It depends on the Khan being pleased, and who knows what will impress such a man.'

'What demonstration do you have in mind?'

'We must manufacture shells containing the Chinese wai jen ti formula, shells that won't break on firing, but will when they hit the ground.'

They tried out several different designs, and even the demonstrations proved quite dangerous; more than once people had to run for their lives. It would be a terrible weapon if it could be made to work. Bahram hurried around all day every day, imagining his family returned, Samarqand saved from infidels; surely if Allah meant these things to be, then the weapon was a gift from Him. It was not hard to overlook the terror of it.

Eventually they manufactured hollow flat backed shells, pumped full of the liquid constituents of the ki I ler of myriads, in two chambers separated by a tin wall. A packet of flashpowder in the nose of the shell exploded on contact, blowing the interior wall apart and mixing the constituents of the gas.

They got them to work about eight times out of ten. Another kind of shell, entirely filled with gunpowder and an igniter, exploded on impact most deafeningly, scattering the shell like fragmented bullets.

They made fifty of each, and arranged a demonstration out on their test grounds by the river. Khalid bought a small herd of broken nags from the gluemaker, with the promise of selling them back ready for rendering. The ostlers staked these poor beasts out at the extreme range of the test cannon, and when the Khan and his courtiers arrived in their finery, looking somewhat bored by now with this routine, Khalid kept his face turned away in as close to a gesture of contempt as he could risk, pretending to attend busily to the gun. Bahram saw that this would not do, and went to Nadir and Sayyed Abdul Aziz and made obeisances and pleasantries, explaining the mechanism of the weapon, and introducing Khalid with a little flourish as the old man approached, sweating and puffing. '

Khalid declared the demonstration ready. The Khan flicked a hand casually, his characteristic gesture, and Khalid gave the sign to the men at the gun, who applied the match. The cannon boomed and expelled white smoke, rolled back. Its barrel had been set at a fairly high angle, so that the shell would come down hard on its tip. The smoke swirled, all stared down the plain at the staked horses; nothing happened; Bahram held his breath A puff of yellow smoke exploded among the horses, and they leapt away from it, two pulling out their stakes and galloping off, a few falling over when the ropes pulled them back. All the while the smoke spread outwards as from an invisible brushfire, a thick mustard yellow smoke, obscuring the horses as it passed over them. It covered one that had burst its tether but charged by accident back into a tendril of the cloud; this was the one they could see rear up in the mist, fall and struggle wildly to get back on its feet, then collapse, twitching.

The yellow cloud cleared slowly, drifting away downvalley on the prevailing wind, seeming heavy and clinging long in the hollows of the ground. There lay two dozen dead horses, scattered in a circle that encompassed two hundred paces at least.

'If there was an army in that circle,' Khalid said, 'then, most excellent servant of the one true God, Supreme Khan, they would be just as dead as those horses. And you could have a score of cannon loaded with such shells, or a hundred. And no army ever born could conquer Samarqand.'

Nadir, looking faintly shocked, said, 'What if the wind changed its course and blew our way?'

Khalid shrugged. 'Then we too would die. It is important to make small shells, that can be fired a long distance, and always downwind, if possible. The gas does disperse, so if the wind was mildly towards you, it might not matter much.'

The Khan himself looked startled at the demonstration, but more and more pleased, as at a new form of fireworks; it was hard to be sure with him. Bahram suspected that he sometimes pretended to be oblivious to things, in order to make a veil between himself and his advisers.

Now he nodded to Nadir, and led his court off on the road to Bokhara.

'You have to understand,' Khalid reminded Bahram on the way back to the compound, 'there are men in that very group around the Khan who want to bring Nadir down. For them it doesn't matter how good our weapon is. The better the worse, in fact. So it's not just a matter of them being utter simpletons.'

These Things Happened

The next day Nadir was out with his full guard, and they had with them Esmerine and the children. Nadir nodded brusquely at Bahram's fulsome thanks and then said to Khalid, 'The poison air shells may become necessary, and I want you to compile as many as you can, five hundred at least, and the Khan will reward you accordingly on his return, and he makes promise of that reward in advance, by the return of your family.'

'He's going away?'

'The plague has appeared in Bokhara. The caravanserai and the bazaars, the mosques and madressas and the Khanaka are all closed. The crucial members of the court will accompany the Khan to his summer residence. I will be making all his arrangements for him from there.

Look to yourselves. If you can leave the city and still do your work, the Khan does not forbid it, but he hopes you can close yourself up here in your compound, and carry on. When the plague passes we can reconvene.'

'And the Manchu?' Khalid asked.

'We have word that they too have been struck. As you might expect. It may be they have brought it with them. They may even have sent their sick among us to pass along the infection. It would be little different than casting poisoned air on an enemy.'