De Gex commanded the Highlanders around him to remain at their posts, and strode toward the round turret. Several of the Scotsmen affected not to have grasped his order, and followed him; but MacIan, who was now aimed for the same door, turned round, his face very choleric, and bit off a few words in Scots that sent them all glancing away. He entered the round turret only two strides ahead of de Gex.

“Pity,” said the latter, looking around the perfectly barren room, “all the astronomical devices are gone.”

Lord Gy was already in the stair, on his way down. “Eh?”

“Didn’t you know? This was where Flamsteed worked, in the days before the Royal Observatory was moved to Greenwich. The Prime Meridian of the English once passed through this room-”

Which was perfectly trivial and beside the point, as de Gex well knew. But he did not like the look on the face of Lord Gy, and wanted to break his concentration. The gambit might have worked on a French nobleman whose social reflexes had been trained to quivering perfection in the salons of Versailles. It failed on Lord Gy, who had ascended to the nobility by cutting such a Frenchman in twain, and who at this moment looked as if he were ready to do it again.

The purpose of the round tower was to support a spiral stair. Finding Jack was a matter of winding down and gazing into each doorway that presented itself. They shortly tracked him down on the middle of the building’s three floors. This space, formerly the royal court of a King, had been given over in recent centuries to the storage of official documents. Jack was squatting with his back to them in the middle of a cavernous fireplace shaking powder from a horn onto the Scottish banner, which he had folded a couple of times and stuffed beneath an andiron. On his career through the former throne-room he had swiped an armload of rolled-up papers from a dusty shelf and piled them under and around the banner to serve as kindling.

“Jacques-” de Gex began.

“Pardon me while I destroy the evidence, your virginity.”

“Ye baistart!” exclaimed Lord Gy.

“Did I say, destroy the evidence?” Jack said, looking over his shoulder to see MacIan. “I meant that this sacred banner became torn and dirtied in the fray, and the only respectful way to dispose of it now is by a cleansing flame.” And he held a pistol-an unloaded one, as it turned out-next to the banner and pulled the trigger. Sparks from the flint sprayed across powder-smeared fabric and became something more than sparks. A fizzy conflagration spread across the banner, like flames across a field of harvested stalks, only faster. Jack recoiled, staggering out of the fireplace to get clear of the smoke. Since a draught had not yet been established in the chimney, a good deal of the smoke followed him-indeed, was sucked into his wake so that he seemed to be trailing it behind him like a rocket. “Right, let’s go somewhere we can breathe,” Jack suggested, and strode past de Gex and MacIan, headed for the stair.

Now de Gex had seen a few duels in his day. These were at least as formal, and as premeditated, as weddings. But he’d also seen a sufficient number of sudden murderous stabbing-brawls to have understood that even they were not as spontaneous as they looked.

If you were strolling in the gardens of Versailles, you might one day hear sudden noises, and turn around to see, some distance away, one fellow-let’s call him Arnauld-going after another-call him Blaise-with a drawn blade. From which, if you were a careless observer, you might think that Arnauld had just snapped without warning, like an ice-covered bough falling from a tree. But in truth the Arnaulds of the world were rarely so reckless. A careful observer, watching Arnauld for two or three minutes prior to the onset of violence, would see some sort of exchange between him and Blaise-a calculated insult from Blaise, let us say, such as a refusal to let Arnauld through a door ahead of him, or a witticism about Arnauld’s wig, which had been so very fashionable three months ago. If Blaise were a polished wit, he would then move on, blithe, humming an air, and giving every appearance of having forgotten the event.

But Arnauld would become a living Exhibit. Symptoms would set in that were so obvious and dramatic as to furnish a topic of study for the Royal Society. Why, a whole jury of English savants could stand around poor Arnauld with their magnifying lenses and their notebooks, observing the changes in his physiognomy, noting them down in Latin and rendering them in labored woodcuts. Most of these symptoms had to do with the Humour of Passion. For a few moments, Arnauld would stand fast as the insult sank in. His face would turn red as the vessels in his skin went flaccid, and consequently ballooned with blood from a heart that had begun to pound like a Turkish kettle-drum signalling the onset of battle. But this was not when the attack came, because Arnauld, during this stage, was physically unable to move. All of his activity was mental. Once he got over the first shock, Arnauld’s first thought would be to convince himself that he had reined in his emotions now, got himself under control, was ready to consider matters judiciously. The next few minutes, then, would be devoted to a rehearsal of the recent encounter with Blaise. Affecting a rational, methodical approach, Arnauld would marshal whatever evidence he might need to convict Blaise of being a scoundrel, and sentence him to death. After that, the attack would not be long in following. But to one who had not been there with those Fellows of the Royal Society to observe all that had led up to it, it would seem like the spontaneous explosion of an Infernal Device.

De Gex was standing behind MacIan and had watched the banner-burning over the other’s epaulets. The backs of MacIan’s ears had gone cherry red. He’d not so much as twitched an eyelid when Jack had strode past him to the stair. De Gex knew what would be coming soon. There was nothing he could say now to interrupt the proceedings going on in MacIan’s brain: the marshalling of the arguments, the sure and inevitable judgment. But there was something he could do. He let his satchel down to the floor, and reached silently into the pocket of his cassock. It was not a lined pocket, but a slit that went all the way through the garment, and gave him access to what was beneath.

Father Edouard was a member of the Society of Jesus, but he was a participant in the society of men-to be specific, the men of London, the most beastly city he had ever seen, though he’d circumnavigated the globe. In his waistband, his fingers found the hilt of a splendid watered-steel dagger he’d picked up from a Banyan in Batavia. He drew it silently from its leather sheath. MacIan still hadn’t moved. The room was silent except for the crackle of the flames spreading to the pile of ancient documents Jack had strewn around the flag. De Gex broke the silence, a little, by stepping forward.

But this triggered a greater sound from behind him. Before de Gex could turn to see what it was, his dagger-hand had been seized from behind and twisted up behind his back. The fingers opened and the weapon dropped, but did not fall to the floor; it was intercepted by another hand. An instant later that hand appeared in front of him and brought the dagger to his throat. He had been embraced from behind by a man who smelled of sweat-sodden wool, of horses, and of gunpowder. One of the Highlanders had tailed him silently down stairs.

“Ye ir a man of kirk, so a sal gie ye benefit of clergy,” said the Highlander into his ear, “binna ye speik sae much as a word, an then it’ll be atwein ye and St. Peter as ti whaur ye sal be expoondin yeir next sermon.”

Rufus MacIan turned around. His ears were no longer red. With barely a glance towards de Gex he strode to the spiral stair and followed Jack down to the first storey.