For three days straight, André shut himself inside the attic.

  Except for eating, drinking, and answering nature’s call, he refused to open the door or speak to anyone.

  “What’s wrong with André? Didn’t we win the final victory?” asked Meldar in confusion.

  Hoche kept his silence; the ever-cheerful Legendre said nothing either, while Inspector Javert cast the Polish boy a glare so sharp it made him flinch. Standing nearby, the housekeeper Anna hurriedly took her nephew to the kitchen.

  The three men stared at each other in wordless stalemate for quite a while—until footsteps sounded on the stairs.

  “Hey, gentlemen. All gathered here to wait for me to have dinner?”

  André appeared with a sunny smile, the last trace of gloom wiped clean from his face.

  “Yes,” Legendre replied quickly.

  André tilted his head, glanced at the pocket watch in his hand, and chuckled.

  “It’s not even three o’clock yet. Let’s have some afternoon tea instead.”

  The landlord shouted toward the kitchen on the ground floor:

  “Anna! Anna! It’s tea time!”

  When André came down to the dining room, he noticed that the tenants of 156 Rue Saint-Jacques were gone.

  Upon asking, Legendre explained that he had paid the two families to move out early—he intended to reserve the entire building for André and his friends.

  André agreed at once.

  He decided to move into the spacious suite on the second floor, which had two bedrooms, a study, and a drawing room—more fitting for the Prosecutor of the Special Fiscal Court.

  Legendre, meanwhile, left a single room on the first floor for Sergeant Hoche.

  In the dining room, André took a sip of champagne and frowned.

  “The quality this year is dreadful.”

  Javert nodded.

  “The vineyards across the whole Champagne region have suffered disease. The grapes have lost their flavour, and the harvest fell by a third.”

  It was clear his sister had sent word through a letter.

  Indeed, in 1790, the Parisian go?ter—their version of afternoon tea—was not accompanied by black tea but by wine, usually champagne, or coffee. The sweets, however, were dazzling in variety: soft and fragrant madeleines, the layered richness of gateau opéra, the airy crispness of mille-feuille, along with cheeses, hams, and sweet oranges—all laid out in abundance.

  After swallowing a mouthful of cake, André seemed to remember something.

  He took a cheque from his breast pocket—tucked between the pages of his chequebook—and handed it to Legendre.

  “Please have it cashed,” he said. “10,000 livres are to be sent immediately to the Reims Orphanage. The rest you will keep on deposit. If anyone among us needs money, they may come to you for it. Any amount below 2,000 livres doesn’t require my signature.”

  “Ten—10,000 livres?”

  Legendre cried out in astonishment when he saw the number. That sum equalled five years of his family’s income—enough to buy two houses in this working-class quarter.

  André had no interest in purchasing a house in central Paris for now. The environment was dreadful—so dreadful that even Londoners, accustomed to filth and chaos, found Paris intolerable.

  The British envoy had complained more than once that Paris was “the dirtiest city in all Europe, bar none.”

  Listening to the conversation between André and the landlord, Hoche and Javert exchanged silent glances of gratitude.

  Unlike the well-off Legendre, they came from humble families; this allowance of 2,000 livres a year would ensure that their relatives lived in comfort, free from the daily struggle of survival.

  André knew it perfectly well: to win men’s hearts and keep shared interests aligned, one must first ensure that everyone had enough gold to exchange. 10,000 livres could excite him for a day or two—but to sustain his grand design, planned in the solitude of the last three days, he would need far more.

  “These funds,” Legendre suggested, “3,000 livres can go to the stock exchange, 5,000 to government bonds, 10,000 to the orphanage, and the rest for household expenses.”

  He spoke with a certain confidence: besides running his own business, he also managed the club’s finances and often dealt with brokers at the Paris Bourse.

  André shook his head at once.

  “From now on, stay away from government bonds entirely,” he said.

  “The Swissman—Necker—won’t stay long as Minister of Finance. He’ll be out by year’s end at the latest. Send 10,000 to Reims, keep another 10 as working capital, put 50,000 into the insurance fund, and buy 30,000 in bonds from the Périer brothers’ Paris Waterworks Company.”

  In recent years, as relations between France and Britain had warmed, the Paris insurance funds had shifted their overseas investments from Rotterdam to London.

  With the British Empire’s Industrial Revolution in full swing and its dominion spanning half the globe, André was certain it was a safe and profitable venture—at least until the rupture of 1793.

  The Paris Waterworks Company, founded in 1777, however, was a more complicated case.

  “Périer brothers?” said Legendre.

  “The water company out west near Chaillot—the present Champs-élysées—that’s been imitating British steam engines? Everyone knows it’s a junk stock. The City Hall concession for their water supply expires in two years.”

  A dishonest broker had once tried to sell him those very bonds, but Legendre had quickly realised the company’s miserable performance and refused without hesitation.

  “Junk stock?” André thought privately. “No, that’s a future tech share—destined for Nasdaq.”

  The water company might be unprofitable, but in their workshops the Périer brothers had spent thirteen years imitating Watt’s steam engines, training over 200 skilled mechanics—and, far more valuable still, a generation of engineers and builders.

  When the time came, a flick of André’s golden finger would unleash the industrial revolution from within that modest enterprise.

  There was no need to explain; he merely told Legendre to follow his instructions precisely.

  “Very well,” Legendre said at last.

  “I know a broker at the market—Ouvrard. Honest and reliable. I’ll have him handle the transactions.”

  André nodded in approval. Then, turning to Hoche, he said:

  “Louis, I’ve already registered you at the école Militaire de Paris. Within the next two or three months, you’ll join the accelerated artillery course.”

  Unlike the more prestigious institutions, the Paris Military School’s accelerated track offered little glamour—officers were still expected to be of noble birth.

  Even after the Revolution, only a quarter of non-noble sergeants could rise to commissioned rank through examinations, and before August 1792, social barriers still blocked most of them.

  Once Hoche passed his exams, he would be qualified as a junior officer.

  As Prosecutor of the Special Fiscal Court, André would soon command a mounted fiscal corps charged with policing tax crimes across the Greater Paris region—and Hoche, as Second Lieutenant, would act as its Commandant.

  “But I’d rather be in the cavalry,” Hoche muttered, squeezing a Mediterranean orange in his hand. “Besides, I’m hopeless at mathematics—I can’t even calculate a simple parabolic arc.”

  A case of content theft: this narrative is not rightfully on Amazon; if you spot it, report the violation.

  André burst out laughing. “A true Commandant must master artillery. When the time is right, I’ll give you your cavalry troop. As for your maths, I’ve already hired a tutor from the public employment bureau. Remember this, my friend—modern warfare is a war of numbers and geometry.”

  Napoleon had won 95% of his battles largely because of his mathematical genius. From the stride of a private he could infer the quality of a regiment; from its marching speed and formation, the calibre of its officers; from the rhythm of cannon fire, the moment when the enemy’s line would crumble.

  Victory was, in essence, a matter of calculation.

  Hoche was no Napoleon.

  He lacked brilliance, but he was diligent, obedient, and dependable—and that, André thought, was enough. He had no patience for temperamental prodigies who argued every order. A sound staff system could make up for any missing genius.

  “Meldar,” André called. The boy was helping in the kitchen but came running at once. “From now on, I won’t have time to teach you French. Sergeant Hoche will. You’ll also join him for mathematics. A year from now, you should be ready to apply to the Sorbonne.”

  Meldar nodded eagerly, cowed as always by the intimidating presence of Inspector Javert.

  While André spoke to the boy, Hoche looked hesitant. Only when André asked directly did he confess:

  “I went to the Tuileries yesterday. Met Lieutenant Lefebvre. He asked me to congratulate you on your victory in court.”

  “Mm,” André replied flatly.

  Hoche went on, “He also wishes to see you again at the Tuileries—he wants to introduce a friend.”

  Lefebvre? André’s smile faded.

  Too loyal to Louis XVI and the Bourbon crown. He had already resolved to sever that tie.

  “No,” he said at first.

  But seeing Hoche’s disappointment, André softened.

  “I’m about to assume public office. It wouldn’t do to be seen at the Tuileries too often. Choose another place. There’s a restaurant called La Méditerranée by the southern entrance of the Place Louis-XV—what they’ll call the Place de la Révolution in two years. It’s decent enough. But I’m busy these days. Let’s say... Pentecost, a month from now.”

  When that troublesome matter was settled, André turned his gaze to Inspector Javert.

  “How goes the murder case at the Chateau de Forny, Comte and Comtesse both?”

  Javert set down his pastry and sighed.

  “The same as before. We’ve confirmed that the Comte repeatedly violated Marisa’s only daughter, the maid named Molly. We’ve also established that the Comtesse used abortive medicines—illegally—and that those caused the girl’s death. Marisa thus had every reason for revenge. Yet the police cannot prove she committed the murder.”

  André pondered a moment, then said, “Two things puzzle me. First—during the autopsy, the dagger that killed the Comte pierced the ribcage and sank nearly to the hilt. That would be nearly impossible for a woman of Marisa’s slight strength. Second—having taken her revenge and lost the only person she loved, she has nothing left to hide. Why keep silent? She could easily expose the Comte’s crimes in court and destroy his reputation. Unless...”

  Javert’s eyes lit up. “Unless she’s protecting an accomplice. The Comte’s nephew, Arbon, is our prime suspect. He inherits the estate—worth 1 million livres on the Right Bank. But Marisa won’t speak. How can we prove it?”

  André smiled faintly.

  “No need to hurry. I’ll prove it with science. Incidentally, delay the case for now. Someone has his eye on the post of Prefect of Police in Paris. Solving this sensational double murder would make a perfect gift for you to present to the new chief.”

  Inspector Javert nodded in silence. He knew André never plotted against his own allies. If André said to wait, he would wait.

  André had intended next to speak with Legendre about the Cordeliers Club, but before he could open his mouth, the housekeeper Anna appeared at the dining-room door, leading in a stranger.

  “Monsieur André,” she said, “this young man is named Fourier. He says the employment bureau sent him to serve as a tutor.”

  “Fourier?” André studied him with interest.

  The visitor was about twenty, tall and slender, with a handsome head of chestnut hair and fine dark eyes behind round spectacles. His worn but tidy clothes, and the stiffness of his posture, betrayed both poverty and timidity.

  One glance was enough for André to classify him: not a tradesman, but a scholar.

  He had known two Frenchmen named Fourier in his previous life. One was an eccentric merchant of Lyon, remembered in political histories; the other, the mathematician whose infernal Fourier Transform had slain half of André’s brain cells back in college.

  He skimmed the résumé from the bureau and found his suspicion confirmed.

  The young man’s full name was Jean-Baptiste Joseph Fourier. Born to a tailor’s family in Auxerre, orphaned at nine, and adopted by a local bishop. He had entered the military school there in 1780 and later taught at his old college. Only a week ago, he had resigned his post and come to Paris to try his fortune.

  “Tell me your terms, Monsieur Fourier,” said André with an affable smile.

  “Three livres a day,” the young man replied quickly. “But if you can offer lodging and meals, 20 sous would be enough.”

  His eyes drifted toward the pastries and wine on the table; hunger had dried his lips.

  “Hahaha! Sit down, my mathematician friend!”

  André pulled him cheerfully into a chair beside him, gestured for Anna to bring another setting, and poured him a glass of champagne himself.

  Same formula, same familiar taste.

  The others looked on, each wondering what quality in this provincial schoolmaster had caught the lawyer’s attention.

  “Three livres a day it is,” André continued. “Our kind-hearted landlord will provide you with board and lodging. Does that suit you?”

  Legendre nodded his consent; there was still a spare room on the ground floor.

  “Monsieur Franck, I’m delighted—truly delighted!” Fourier gulped down the wine and nodded gratefully.

  Though puzzled by the generous terms, he trusted that a famous lawyer and soon-to-be Prosecutor of the Special Fiscal Court would have no need to deceive a penniless provincial.

  When the tea was done, André led Inspector Javert up to the attic, leaving Hoche, Meldar, and their new teacher to explore the wonders of mathematics in the dining room, while Legendre went to the bank with the cheque.

  Upstairs, André dragged a wooden chest to the desk, slipped on a pair of long white gloves, and drew out a blunt dagger. He handed it to Javert, then took it back again.

  He smiled.

  “And now, Monsieur Javert, I shall prove—with iron evidence—that you have just committed a perfectly planned murder.”

  The inspector stared, bewildered. For a moment, his mind was blank—then he caught on.

  “You mean,” he asked, “you can prove it was the Comte’s nephew who stabbed him?”

  “Of course,” André said, his expression proud.

  Before the inspector could reply, André began laying out his tools on the table: a small box of black magnetic powder and a soft feather duster made of fine wool.

  He dipped the duster into the powder, shook it lightly, and brushed it across the dagger’s surface—slow, circular motions, each stroke leaving behind a delicate film of black dust.

  This, unknown to eighteenth-century France, was one of the basic fingerprint techniques used by detectives a century later. The world’s first documented fingerprint identification had taken place in Argentina in 1892, where police used this “new science” to solve a murder—an event that caused an international sensation.

  Some Europeans later claimed that the Argentines had been inspired by Arthur Conan Doyle’s A Study in Scarlet, published in 1886, but whatever its origin, fingerprinting had revolutionised forensic science forever.

  In his former life, André had studied it extensively—both as a student and as a Holmes devotee—and reproducing the tools of a future century had been almost effortless for him.

  For non-porous surfaces such as metal, glass, or porcelain, there was an even more effective technique known as iodine fuming: heating iodine crystals to release vapour that reacted with the oils of latent prints, turning them a visible brown.

  Soon enough, to Javert’s astonishment, his own fingerprints stood out clearly on the dagger’s surface, traced in black powder.

  André removed his gloves and pointed to them.

  “Under normal conditions,” he explained, “the human finger is covered with a thin layer of sweat and oil. When it touches an object, it leaves behind a unique ridge pattern. The Académie des Sciences proved, in its 1788 journals, that no two fingerprints are ever the same—just as no two leaves are identical.”

  He paused, then added, “Of course, one must not rush. First, you’ll need to use the method in one or two minor cases—gain support from the criminal prosecutor, secure a judge’s approval as valid physical evidence.

  “Then, with help from the newspapers and the authority of the Académie, a little scientific publicity will do the rest. When the time is right, the real killer at the Forny estate will have nowhere left to hide.”

  Javert’s eyes shone.

  This wasn’t merely a convenient method—it was a discovery that could change policing itself. And then came André’s final instruction, delivered with an impish half-smile:

  “Speak of it to no one. In truth, Monsieur Javert, this brilliant method was invented by you—during your service as a prison warden.”

  Tuileries Palace, the office of the Minister of Finance.

  Spacious, opulent, and steeped in the fragrance of mahogany and ink.

  The ever-gracious Jacques Necker, his face framed by the habitual serenity of a banker-statesman, had just dismissed his last visitor. He called to his secretary through the half-open door:

  “Tell them I need an hour’s rest. No interruptions.”

  Abandoning the high-backed walnut chair that symbolised ministerial dignity, he reclined on the sofa, soft as a featherbed. Sleep, however, refused to come. The machinery of the kingdom—its debts, deficits, and dissensions—whirred endlessly in his head.

  The most recent vexation came from his old friend Condorcet: a polite but impossible request—protect the Fermiers Généraux, the tax-farmers.

  No one understood their power better than Necker himself.

  Before the Revolution, the tax-farming system had been an empire within the kingdom: over 700 officials divided among secretariats, accounting bureaus, customs offices, the salt and excise departments, and a committee staffed by ten lawyers and a single parliamentary agent. They controlled the collection of duties from France and her colonies, serving the interests of 128 tax-farmers—men of enormous fortune and influence.

  The strength of the system had once lain in its efficiency. By holding the right to collect the surplus revenue, the farmers had every incentive to innovate and increase yield—far more effective than the lumbering bureaucracy of direct taxation.

  But greed had corroded that efficiency, transforming the tax-farming system into a national parasite. By 1789, public resentment was white-hot.

  When the Revolution erupted, their grand offices were besieged and burned.

  The survivors fled to the outskirts of Paris; their operations stagnated; their contributions to the treasury dwindled as they delayed, evaded, or outright refused payment.

  From the standpoint of the state, Necker admitted, André’s forthcoming prosecutions as Prosecutor of the Special Fiscal Court were justifiable—perhaps even necessary. Recovering 100 million livres in unpaid taxes could shore up the tottering finances of France.

  Yet from a banker’s point of view, the attack on the tax-farming system was perilously close to an attack on his own kind.

  Bankers and tax-farmers were, after all, creatures of the same species—offspring of credit and speculation. Necker’s own fortune had been spun from precisely such webs of privilege and debt.

  Condorcet had said it plainly:

  “This universal condemnation of the tax-farmers is, in truth, a condemnation of every effort we made before 1789.”

  Today the Prosecutor of the Special Fiscal Court might haul the tax-farmers before a tribunal; tomorrow, the same logic could be turned against bankers, and Necker himself might find his private accounts paraded before the Assembly.

  No—he must stand with the tax-farming system, at least this once.

  Resolved, Necker rang for his secretary again.

  “Go to the Manège Hall,” he ordered, referring to the building that housed the Constituent Assembly beside the Tuileries. “Ask for my old friend—and rival—the lion of the Assembly himself: Comte de Mirabeau. Tell him the Minister of Finance would like to invite him for afternoon tea.”