It probably had not even occurred to that Winged Hussar that Jack would know how to ride. In his part of the world, a serf could no more ride on horseback than he could speak Latin or dance a minuet. And disobeying the command of an armed lord was even less likely than riding around on a horse.

But Jack was not Polish scum of the earth, barefoot and chained to the land, or even French scum of the earth, in wooden clogs and in thrall to the priest and the tax-farmer, but English scum of the earth in good boots, equipped with certain God-given rights that were (as rumor had it) written down in a Charter somewhere, and armed with a loaded gun. He mounted the horse like a lord, spun it round smartly, reached back and slapped it on the ass, and he was off. In a few moments he had ridden through the middle of that knot of men who were hoping to catch the giant bird. Their only hope had been that their prey would forget that it was being chased, and stop running. Jack had no intention of letting that happen and so he jabbed his boot-heels into his mount’s sides and lit out after the bird in a way that was calculated to make it run like hell. Which it did, and Jack galloped after it, far outdistancing his competition. But the bird was astoundingly swift. As it ran, its wings splayed this way and that like an acrobat’s balancing-pole. Seeing into those wings from behind, Jack was reminded of decorations he’d seen in the hats of fine French gentlemen, and their mistresses, during military parades: those were the plumes of the, what’s it called the, the… the ostrich.

The reason for this merry chase was plain now: the ostrich, if caught, could be plucked, and its plumes taken to markets where fine things from exotic lands were sold, and exchanged for silver.

Now, Jack calculated. If he scoured the entire Turkish camp, he might find finer things to loot-but the legions of Christendom were all running wild through this place and others were likely to have found them first. The finest things of all would be taken by lords on horseback, and the musketeers and pikemen would be left to brawl over trifles. The plumes of this ostrich were not the finest prize to be had in this camp, but a bird in the hand was worth two in the bush, and this one was almost in his hand. Ostrich-plumes were small and light, easy to conceal from the prying fingers and eyes of customs men, no burden to carry all the way across Europe if need be. And as the chase continued, his odds only improved, because this ostrich was speeding away from all noise and commotion, tending toward parts of the Grand Turk’s camp where nothing was going on. If only it would hold still long enough for him to bring it down with a musket-shot.

The ostrich flailed, squawked, and vanished. Jack reined in his mount and proceeded carefully, and arrived at the lip of a trench. He hadn’t the faintest idea where he was, but this trench looked like a big one. He nudged the horse forward, expecting it to balk, but it cheerfully set to work, planting its hooves carefully in the loose earth of the trench’s sloping wall and picking its way down. Jack saw fresh ostrich prints in the muck on the bottom, and set the horse to trotting that direction.

Every few yards a smaller trench intersected this one at right-angles. None of these trenches had the palisades of sharpened outward-pointing sticks that the Turks would’ve installed if they’d been expecting an attack, and so Jack reckoned that these trenches did not belong to the camp’s outer works, which had been put up to defend it from encircling armies of Christians. These trenches must, instead, be part of the assault against Vienna. The smoke and dust were such that Jack could not see whether the city was ahead of, or behind, him and the ostrich. But by looking at the way that the earth had been piled up to one side of those trenches, to protect the inhabitants from musketballs, any fool could make out in which direction the city lay. The ostrich was going towards Vienna, and so was Jack.

The walls of the big trench steadily became higher and steeper, to the point where they’d had to be shored up with pilings and retaining walls of split logs. Then all of a sudden the walls curved together above him, forming an arch. Jack reined the horse in and stared forward into a dark tunnel, large enough for two or three horsemen to ride abreast. It was cut into the foundation of a steep hill that rose abruptly from generally flat land. Through a momentary parting in the drifting clouds of smoke, Jack looked up and saw the mutilated face of the great bastion looming up above him, and glimpsed the high roof of the Emperor’s Palace beyond and above that.

This must be a mine, an enormous one, that the Turks had dug beneath the bastion in the hopes of blowing it to kingdom come. The tunnel floor had been paved with logs that had been mostly driven down into the mud by the weight of oxen and wagons as they hauled dirt out, and gunpowder in. In the mud, Jack could see ostrich-prints. Why should that bird settle for merely burying its head in the sand when it could go wholly underground, and not even have to bend over? Jack did not love the idea of following it, but the die was cast; loot-wise, it was the ostrich or nothing.

As one would expect in any well-organized mining operation, torches were available near the entrance, soaking head-down in a pot of oil. Jack grabbed one, shoved it into the coals of a dying fire until flames emerged, then rode his horse forward into the tunnel.

It had been carefully timbered to keep it from collapsing. The tunnel descended gently for some distance, until it pierced the water table and became a sort of unpleasant mire, and then it began to climb again. Jack saw lights burning ahead of him. He noticed that the floor of the tunnel was striped with a bright line of steaming blood. This triggered what little Jack had in the way of prudent instincts: he threw the torch into a puddle and nudged the horse along at a slow walk.

The lights ahead of him illuminated a space larger than the tunnel: a room that had been excavated, deep underneath-where? Thinking back on the last few minutes’ ride, Jack understood that he had covered a considerable distance-he must have passed all the way beneath the bastion-at least as far as the city’s inner wall. And as he drew closer to the lights (several large torchieres), he could see that the Turks’ tunnel-work, and its supporting timbers, were all involved with things that had been planted in the earth hundreds of years ago: tarred pilings, driven in one alongside the next, and footings of mortared stone and of brick. The Turks had burrowed straight through the foundations of something enormous.

Following the rivulet of blood into the illuminated space, Jack saw a few small, bright, billowing tents that had been pitched, for some unfathomable Turkish reason, in the middle of this chamber. Some were standing, others had collapsed into the dirt. A pair of men were striking those gay tents with curt sword-blows. The ostrich stood to one side, cocking its head curiously. The tents tumbled to the floor with blood flying out of them.

There were people in those tents! They were being executed, one by one.

It would be easy to kill the ostrich here with a musket-shot, but this would certainly draw the attention of those Turkish executioners. They were formidable-looking fellows with handsome sabers, the only Turks Jack had laid eyes on today who were actually alive, and the only ones who were in any condition to conduct violence against Christians. He preferred to leave them be.

A saber struck at the top of one of those colorful tents, and a woman screamed. A second blow silenced her.

So, they were all women. Probably one of those famous harems. Jack wondered, idly, whether the mudlarks of East London would ever believe him if he went home and claimed he had seen a live ostrich, and a Turk’s harem.