'It must be a small fire, or they would burn the bag. A brazier using charcoal, you wouldn't see that. Then when they want to come down, they damp the fire.'

'I want to do that,' the Sultan declared. 'Why didn't you make one of these for me?'

'I didn't think of it.'

Now the Sultan was in especially high spirits. The red floating bag was floating their way.

'We can hope the winds carry it elsewhere,' Ismail remarked as he watched it.

'No!' the Sultan cried. 'I want to see what it can do.'

He got his wish. The floating bag drifted over the palace, just under the clouds, or between them, or even disappearing inside one, which gave Ismail the strongest sense yet that it was flying in the air like a bird. People in the air like birds!

'Shoot them down!' the Sultan was shouting enthusiastically. 'Shoot the bag!'

The palace guards tried, but the cannon that were left standing on the broken walls could not be elevated high enough to fire at it. The musketeers shot at it, the flat cracks of their muskets followed by shouts from the Sultan. The acrid smoke of gunpowder filled the grounds, mixing with the smells of citrus and jasmine and pulverized dust. But as far as any of them could tell, no one hit bag or basket. Judging by the minute faces looking down from the basket's edge, wrapped in heavy woollen scarves it appeared, Ismail thought they were perhaps out of range, too high to be hit. 'The bullets probably won't go that far up,' he said.

And yet they would never be too high to drop things on whatever lay below. The people in the basket appeared to wave at them, and then a black dot dropped like a stooping hawk, a hawk of incredible compaction and speed, crashing right into the roof of one of the inner buildings, exploding and sending shards of tile clattering all over the courtyard and garden.

The Sultan was shouting ecstatically. Three more gunpowder bombs dropped onto the palace, one on a wall where soldiers surrounded one of the big guns, killing them with much damage.

Ismail's ears hurt more from the Sultan's roars than from the explo sions. He pointed to the iron ships. 'They're coming in.'

The ships were close onshore, launching boats filled with men. The bombardment from other ships continued during the disembarking, more intense than ever; their boats were going to land uncontested at a section of the city walls they had blasted down. 'They'll be here soon,' Ismail ventured. Meanwhile the floating bag and basket had drifted west, past the palace and over the open fields beyond the city wall.

'Come on,' Selim said suddenly, grabbing Ismail by the arm. 'I need to hurry.'

Down broken marble stairs they ran, followed by the Sultan's immediate retinue. The Sultan led the way into the warren of rooms and passageways deep beneath the palace.

Down here oil lamps barely illuminated chambers filled with the loot of four Ottoman centuries, and perhaps Byzantine treasure as well, if not Roman or Greek, or Hittite or Sumerian; all the riches of the world, stacked in room after room. One was filled entirely with gold, mostly in the form of coins and bars; another with Byzantine devotional art; another with old weapons; another with furniture of rare woods and furs, another with chunks of coloured rock, worthless as far as Ismail could tell. 'There won't be time to go through all this,' he pointed out, trotting behind the Sultan.

Selim just laughed. He swept through a long gallery or warehouse of paintings and statues to a small side room, empty except for a line of bags on a bench. 'Bring these,' he ordered his servants as they caught up; then he was off again, sure of his course.

They came to staircases descending through the rock underlying the palace: a strange sight, smooth marble stairs dropping through a craggy rock hole into the bowels of the Earth. The city's great cisterncavern lay some way to the south and east, as far as Ismail knew; but when they came down into a low natural cave, floored by water, they found a stone dock, and moored to it, a long narrow barge manned by imperial guards. Torches on the dock and lanterns on the barge illuminated the scene. Apparently they were in a side passage of the cistern cavern, and could row into it.

Selim indicated to Ismail the roof around the stairwell, and Ismail saw that explosives were packed into crevices and drilled holes; when they were off and some distance away, this entrance would presumably be demolished, and some part of the palace grounds might fall onto it; in any case their escape route would be obscured, and pursuit made impossible.

Men busied themselves with loading the barge, while the Sultan inspected the charges. When they were ready to leave he himself lit their fuses, grinning happily. Ismail stared at the sight, which had the lamplit quality of some of the Byzantine icons they had passed in the treasure hoards. 'We'll join the Balkan army, and cross the Adriatic into Rome,' the Sultan announced. 'We'll conquer the West, then come back to smite these infidels for their impudence!'

The bargemen cheered on cue from their officers, sounding like thousands in the echoing confinement of the underground lake and its sky of rock. The Sultan took the acclaim with open arms, then stepped onto the barge, balanced by three or four of his men. No one saw Ismail turn and dash up the doomed stairs to a different destiny.

Chapter Two. Travancore

More bombs had been rigged by the Sultan's bodyguards to blow up the cages in the palace zoo, and when Ismail climbed back up the stairs and re emerged into the air, he found the grounds in chaos, invaders and defenders alike running around chasing or fleeing from elephants, lions, cameleopards and giraffes. A pair of black rhinoceroses, looking like boars out of a nightmare, charged about bleeding through crowds of shouting, shooting men. Ismail raised his hands, fully expecting to be shot, and thinking escape with Selim might have been all right after all.

But no one was being shot except the animals. Some of the palace guard lay dead on the ground, or wounded, and the rest had surrendered and were under guard, and much less trouble than the animals. For now it looked as if massacre of the defeated was not part of the invaders' routine, just as rumour had had it. In fact they were hustling their captives out of the palace, as booms were shaking the ground, and plumes of smoke shooting out of windows and stairwells, walls and roofs collapsing: the rigged explosions and the maddened beasts made it prudent to vacate Topkapi for a while.

They were regathered to the west of the Sublime Porte, just inside the Theodosian Wall, on a parade ground where the Sultan had surveyed his troops and done some riding. The women of the seraglio, in full chador, were surrounded by their eunuchs and a wall of guards. Ismail sat with the household retinue that remained: the astronomer, the ministers of various administrative departments, cooks, servants and so on.

The day passed and they got hungry. Late in the afternoon a group of the Indian army came among them with bags of flatbread. They were small dark-skinned men.

'Your name, please?' one of them asked Ismail.

'Ismail ibn Mani al Dir.'

The man drew his finger down a sheet of paper, stopped, showed another of them what he had found.

The other one, now looking like an officer, inspected Ismail. 'Are you the doctor, Ismail of Konstantiniyye, who has written letters to Bhakta, the abbess of the hospital of Travancore?'

'Yes,' Ismail said.

'Come with me, please.'

Ismail stood and followed, devouring the bread he had been given as he went. Doomed or not, he was famished; and there was no sign that he was being taken out to be shot. Indeed the mention of Bhakta's name seemed to indicate otherwise.