Fache was in utter incomprehension of this woman's gall. Not only had she just barged in on Fache without permission, but she was now trying to convince him that Sauniere, in his final moments of life, had been inspired to leave a mathematical gag?

"Une plaisanterie numerique?" Bezu Fache was livid, glaring at Sophie Neveu in disbelief. A numeric joke? "Your professional assessment of Sauniere's code is that it is some kind of mathematical prank?"

"This code," Sophie explained in rapid French, "is simplistic to the point of absurdity. Jacques Sauniere must have known we would see through it immediately." She pulled a scrap of paper from her sweater pocket and handed it to Fache. "Here is the decryption."

"This is it?" he snapped. "All you did was put the numbers in increasing order!"

Fache looked at the card.

Fache's tone lowered to a guttural rumble. "Agent Neveu, I have no idea where the hell you're going with this, but I suggest you get there fast." He shot an anxious glance at Langdon, who stood nearby with the phone pressed to his ear, apparently still listening to his phone message from the U. S. Embassy. From Langdon's ashen expression, Fache sensed the news was bad.

1, 1, 2, 3, 5, 8, 13, 21

Sophie actually had the nerve to give a satisfied smile. "Exactly."

"This is the Fibonacci sequence," she declared, nodding toward the piece of paper in Fache's hand. "A progression in which each term is equal to the sum of the two preceding terms."

"Captain," Sophie said, her tone dangerously defiant, "the sequence of numbers you have in your hand happens to be one of the most famous mathematical progressions in history."

Fache studied the numbers. Each term was indeed the sum of the two previous, and yet Fache could not imagine what the relevance of all this was to Sauniere's death.

"Mathematician Leonardo Fibonacci created this succession of numbers in the thirteenth-century. Obviously there can be no coincidence that all of the numbers Sauniere wrote on the floor belong to Fibonacci's famous sequence."

Fache was not aware there even existed a mathematical progression that qualified as famous, and he certainly didn't appreciate Sophie's off-handed tone.

Fache stared at the young woman for several moments. "Fine, if there is no coincidence, would you tell me why Jacques Sauniere chose to do this. What is he saying? What does this mean?"

Stunned, Fache watched her disappear into the darkness. Is she out of her mind? Sophie Neveu had just redefined le suicide professionnel.

Fache took a menacing step forward, placing his face only inches from Sophie's. "I certainly hope you have a much more satisfying explanation than that."

She shrugged. "Absolutely nothing. That's the point. It's a simplistic cryptographic joke. Like taking the words of a famous poem and shuffling them at random to see if anyone recognizes what all the words have in common."

Sophie's soft features grew surprisingly stern as she leaned in. "Captain, considering what you have at stake here tonight, I thought you might appreciate knowing that Jacques Sauniere might be playing games with you. Apparently not. I'll inform the director of Cryptography you no longer need our services."

Fache turned to Langdon, who was still on the phone, looking more concerned than before, listening intently to his phone message. The U. S. Embassy. Bezu Fache despised many things… but few drew more wrath than the U. S. Embassy.

With that, she turned on her heel, and marched off the way she had come.

And the embassy invariably did just that.

Fache and the ambassador locked horns regularly over shared affairs of state-their most common battleground being law enforcement for visiting Americans. Almost daily, DCPJ arrested American exchange students in possession of drugs, U. S. businessmen for soliciting underage Prostitutes, American tourists for shoplifting or destruction of property. Legally, the U. S. Embassy could intervene and extradite guilty citizens back to the United States, where they received nothing more than a slap on the wrist.

"Is everything all right?" Fache asked.

L'emasculation de la Police Judiciaire, Fache called it. Paris Match had run a cartoon recently depicting Fache as a police dog, trying to bite an American criminal, but unable to reach because it was chained to the U. S. Embassy.

Weakly, Langdon shook his head.

Not tonight, Fache told himself. There is far too much at stake.

By the time Robert Langdon hung up the phone, he looked ill.

Bad news from home, Fache sensed, noticing Langdon was sweating slightly as Fache took back his cell phone.

Fache had no doubt the shock on Langdon's face was genuine, and yet he sensed another emotion there too, as if a distant fear were suddenly simmering in the American's eyes. "I'm sorry to hear that," Fache said, watching Langdon closely. "Would you like to sit down?" He motioned toward one of the viewing benches in the gallery.

"An accident," Langdon stammered, looking at Fache with a strange expression. "A friend…" He hesitated. "I'll need to fly home first thing in the morning."

Fache frowned inwardly at the delay. "The rest room. Of course. Let's take a break for a few minutes." He motioned back down the long hallway in the direction they had come from. "The rest rooms are back toward the curator's office."

Langdon hesitated, pointing in the other direction toward the far end of the Grand Gallery corridor. "I believe there's a much closer rest room at the end."

Langdon nodded absently and took a few steps toward the bench. He paused, looking more confused with every moment. "Actually, I think I'd like to use the rest room."

Fache realized Langdon was right. They were two thirds of the way down, and the Grand Gallery dead-ended at a pair of rest rooms. "Shall I accompany you?"

Fache was not wild about the idea of Langdon wandering alone down the remaining length of corridor, but he took comfort in knowing the Grand Gallery was a dead end whose only exit was at the other end-the gate under which they had entered. Although French fire regulations required several emergency stairwells for a space this large, those stairwells had been sealed automatically when Sauniere tripped the security system. Granted, that system had now been reset, unlocking the stairwells, but it didn't matter-the external doors, if opened, would set off fire alarms and were guarded outside by DCPJ agents. Langdon could not possibly leave without Fache knowing about it.

Langdon shook his head, already moving deeper into the gallery. "Not necessary. I think I'd like a few minutes alone."

"I need to return to Mr. Sauniere's office for a moment," Fache said. "Please come find me directly, Mr. Langdon. There is more we need to discuss."

Turning, Fache marched angrily in the opposite direction. Arriving at the gate, he slid under, exited the Grand Gallery, marched down the hall, and stormed into the command center at Sauniere's office.

Fache looked around. "Is she gone?"

"Who gave the approval to let Sophie Neveu into this building!" Fache bellowed.

Collet was the first to answer. "She told the guards outside she'd broken the code."

"She's not with you?"

"She left." Fache glanced out at the darkened hallway. Apparently Sophie had been in no mood to stop by and chat with the other officers on her way out.

Langdon gave a quiet wave as he disappeared into the darkness.

Pushing Sophie from his mind, Fache stared for a moment at the miniature knight standing on Sauniere's desk. Then he turned back to Collet. "Do you have him?"

For a moment, Fache considered radioing the guards in the entresol and telling them to stop Sophie and drag her back up here before she could leave the premises. He thought better of it. That was only his pride talking… wanting the last word. He'd had enough distractions tonight.

Deal with Agent Neveu later, he told himself, already looking forward to firing her.

"Good," Fache said, lighting a cigarette and stalking into the hall.

Collet gave a curt nod and spun the laptop toward Fache. The red dot was clearly visible on the floor plan overlay, blinking methodically in a room marked TOILETTES PUBLIQUES.

I've got a phone call to make. Be damned sure the rest room is the only place Langdon goes."