"They're gentlemen," I say cautiously. "Who've been given titles. Marquises and barons and so on. They gather at the palace, and they sit around and talk."

"Imagine," says Charles. "Doing nothing all day but talking."

And, as if chastened, our own conversation tapers down. We leave the garden behind, we stroll north on the Rue de Seine, gathering speed as we go, and we're nearly to the Pont des Arts when we are stopped by a backward swell of bodies. The Parisian people, quite oblivious to most vehicles, are making an exception for one. A golden coach of ridiculous proportions, surrounded by silver-trimmed, saber-wielding bodyguards.

"Oh, look," says Charles. "It's got lilies painted on it. Come along, Hector! "

In later years, I confess, I won't be able to trust my account of this moment. Surely it couldn't have happened as easily as all that? On our very first day abroad?

And yet the King's carriage is a common enough sight in these early days of the Restoration. Invalided by gout and obesity, Louis the Eighteenth compensates by setting his carriage loose through the streets of Paris at ever-greater speeds. More than one of his subjects has known the sensation of narrowly escaping the royal cavalcade's progress-and being rewarded with the cool, incurious stare of His Majesty as the carriage shoots past.

Today, however, that journey is foiled by an advance party of pigs, fording the street and cinching the royal carriage into stillness.

"Is that the King?" whispers Charles.

Who else? I want to answer. Who else would be sitting in a posture of such erect indolence? With a litter of white satin cushions to buffer him from any collision?

Across from the King sits the captain of the guard, and next to him, leaning into the window's frame and registering, in the curve of his mouth, a twining of pique and amusement. . . .

There sits Vidocq.

NO . The figu re slowly reconfigures itself. No, not Vidocq. Vidocq as he might look in twenty years. The reserves of f lesh melted away by respectability, the expression of animal absorption refined down into large, encompassing eyes.

"That man must be very good friends with the King," says Charles, "to be sitting so close."

"Not friends at all. They're merely related."

"Related how?"

"Well, that man is the Comte d'Artois. The King's younger brother."

"How funny." Charles reaches under his wig, gives his scalp a good long scratch. "I never think of kings having brothers or sisters, but I suppose they must. Are there any others?"

"Brothers, you mean? There was an older one."

An unfortunate gentleman, thickly built, thickly walled. Handed the keys to the manor just as the serfs were bashing down the door. He married an Austrian princess, and they had a boy who was thrown into a great black tower and never came out alive.

We all know that. We know what's possible, and this is not possible: that this same boy could still be alive, a grown man, pressed into a throng of Parisians, watching his two uncles drive past without even recognizing them. Such things don't happen.

But when I look up and feel the eyes of the Comte d'Artois on me, it's as if the space between us has contracted. I hear a voice behind me say:

"Marie! He's looking this way."

And another voice:

"Ooh, such a handsome figure of a man. Regular cavalier. Everyone says Monsieur has the finest manners in the world."

It's i m portan t to say that there's nothing strange in that address. Monsieur is simply the honorary title bestowed on a king's younger brother. But the Monsieur I'm pondering in this moment is that other fellow, the mastermind first mentioned by Tepac's assassin. The Monsieur who revealed himself as only a voice and a title. Who sat behind a confessional screen and sent Herbaux on that deadly errand to SaintCloud. Sent him to kill a king.

And why has it taken me so long to see? That there is, in all of Paris, one particular Monsieur who would loathe the prospect of longlost kings laying claims to the crown that will one day be his.

"Charles," I whisper. "Turn away."

"What?"

"Turn away."

And as I fasten onto his arm and drag him away, a new fact, stark and plain, leaps out at me.

We've just presented ourselves to him.

MON S I E U R .

CHAPTE R 3 0.

Vidocq Takes an Overdue Interest in Art "Le t me make sure I've got this right, Hector."

I'm back in Vidocq's office, and he's reclining once more in his black leather armchair, wedging his shoes against the rim of his mahogany desk.

"The King's brother," he says, "the Comte d'Artois, has decided that a certain young man named Charles Rapskeller is really the longlost Louis the Seventeenth. Rather than let this young fellow claim his rightful throne, he hires a pair of assassins. Scoundrels from the Parisian underworld who manage, in the way of scoundrels, to get the wrong man. Artois doesn't know it, though, until yesterday afternoon when he just happens to drive by and see this same Charles Rapskeller staring out at him from beneath an ambassador's wig. . . ."

This is what's changed between us. I no longer quail before his skepticism.