Tracy massaged her temples with her index fingers. “What were the robbers looking for?”

“No one knows for sure. It may have been as simple as petty theft, or it could have been government sponsored espionage. The fact is that the monastery was much more secure and it is likely that Jefferson would have felt comfortable leaving important items there.”

“That still doesn’t explain why the French security services were so interested in the box, or what the box was doing walled up in some building in the first place,” said Harvath.

Nichols attempted to explain. “The box belonged to the third American president and many of the documents inside were encoded. The French have an obsession with codes. They never broke any of Jefferson’s, so when the opportunity to get their hands on items he had encrypted popped up, they jumped on it. The only problem for them, though, was that the codes were created using an ingenious machine Jefferson had invented while living in Paris called the wheel cipher.”

“What’s a wheel cipher?”

“Imagine twenty-six wooden discs, like donuts or circular coasters with a hole drilled through the center of each. They were a quarter of an inch thick and four inches in diameter with the letters of the alphabet printed randomly around the edge. The donuts slid onto a metal axle, the protruding edges of which allowed it to be placed in a special rack. From there the discs could be rotated at will to spell out the desired message.

“For the message to be decoded, the recipient not only needed their own wheel cipher, but they also needed to know the order in which to place the wooden wheels along the axle. Without that information, any encoded message was useless.”

“And along with the encoded documents,” said Harvath, “Jefferson’s copy of Don Quixote was in that box?”

“Yes,” replied Nichols.

“What was in the documents?”

“From what we can tell, some of his early work on the missing Koran text. The bulk of what we have been able to piece together from other documents is all encrypted and our best guess is that he used his wheel cipher to do it. To unlock that information, though, we need to know how he ordered his discs.”

“Which means you have a Jefferson wheel cipher,” said Tracy.

“We do.”

Harvath was impressed. “And the key to placing the discs on the axle is what’s inside Jefferson’s Don Quixote?”

“Yes,” said Nichols. “For whatever reason-the sensitivity of the information or concern over what his many enemies might do with it-Jefferson encoded most of his research. In fact, some of the entries in his presidential diary, as well as most of the pages of notes that President Rutledge has acquired and hopes may pertain to Mohammed’s missing revelation are encoded. That’s a large part of why I was hired.”

“To help the President decipher the codes?” asked Tracy.

The professor nodded.

“But why would Jefferson have left the box behind when he returned to America?” inquired Harvath.

“Because,” said Nichols, “when he left, he didn’t know he wouldn’t be coming back. He was barely off the boat back in America before George Washington asked him to accept a position as his secretary of state. Congress moved quickly to approve the appointment and Jefferson’s life changed in the blink of an eye.”

“But he would have sent for his things.”

“Of course he did. But in 1789 he couldn’t just pick up a phone. Arrangements had to be made and they took time. The French Revolution was in full swing and before he could claim his belongings from the Carthusian monastery, it had been sacked and burned by the Parisian mobs.”

“And with it, presumably, the belongings Jefferson had left there,” said Tracy, “including the hidden box.”

“So where’s the Don Quixote now?” asked Harvath. “Do the French have it?”

“No. The laborers suspected they were under surveillance and recruited the two teens that were killed to deliver the rest of the cache to several intermediaries.

“The boys were leaving a meeting with the laborers when the French authorities decided to move in. They were hoping to get the two laborers who were the ringleaders, but the men gave them the slip. The boys were the next best thing. The authorities pursued the teens, but we know how that ended.

“The laborers disappeared, presumably back to North Africa. The French are rumored to have retrieved some of the documents, but they never got the book-probably because they didn’t realize its significance and their focus was on the documents themselves.

“A friend of one of the teens filled in the pieces for the security services, confirming most of what they’d already learned in their investigation. A CIA operative based out of the American Embassy was having dinner with a French counterpart who filled her in on the whole case. The Frenchman thought it would be amusing to her because of the Jefferson connection. She reported back to the head of station, who briefed Langley, and the report made it to the president, who shared it with me.

“When I discovered that a rare first-edition Don Quixote was going to be on sale at this year’s International Antiquarian Book Fair here in Paris, I contacted the dealer, and without tipping my hand, made an inquiry into the provenance of the book. He was somewhat standoffish, but the book world is filled with strange characters.

“He agreed to send me scans of the first couple of pages. There was an annotation and it looked to be a match for Jefferson’s handwriting. I made an appointment to see him so I could examine the book.

“When I got there, he told me he had already decided to sell the book to someone else. Nothing I could do would persuade him. Someone had offered him a lot more money for it. The president couldn’t raise that kind of money; at least not right away.”

Harvath raised an eyebrow. “The president had trouble getting funding?”

“This isn’t a government operation. He has been financing this out of his own pocket. I asked the dealer to agree to wait until close of business today before he went through with the other party. He gave me until three o’clock.

“I was leaving the meeting when I passed you and the bomb detonated.”

“When we first saw you, you were coming out of a bookstore. Does the dealer work there?”

“No, the store has a small café in back. He wanted a neutral place to meet. He’s very paranoid.”

As he should be, thought Harvath. And so should you. Nichols was in way over his head. “Do you have any idea who is bidding against you?” he asked.

“A first-edition Don Quixote with all of its original mistakes that Cervantes personally corrected for the next edition? It could be any bibliophile or lover of literary history.”

“Or it could be the people who have been trying to kill you,” said Harvath as he looked at Tracy. “I think we need to find out.”