“I think it’s possible they knew each other, had communicated. I think it’s possible Captain Cook, who was the more senior of the men, made a promise to Bougainville in exchange for a favor.”

“A hesitation. A pause,” said Mr. Blake. “It wouldn’t seem much, but it cost the colony.”

“And many lives, including Général Montcalm,” said Gamache.

“And in exchange? What would Bougainville get?”

“Perhaps Cook pointed him toward the West Indies. Perhaps Cook turned his own blind eye and let Bougainville map and navigate some important places. I don’t know. That’s why I’m here.” He held up his book. “I suspect I’m wrong and it really was just a coincidence.”

“But it passes the time,” said Mr. Blake. “And sometimes that’s a blessing.”

Avec le temps, thought Gamache. “And you?” he asked the elderly man.

Mr. Blake handed him the book on ancient Scottish grasses. “Ironically, now that I’m so near the end of my life I seem to have all the time in the world.”

Gamache looked at the dry volume, trying to feign interest. Reading this would certainly make an hour seem an eternity. It would stretch, if not actually waste, time. He opened it. A first edition he noticed, but water damaged and so obscure it almost certainly wouldn’t be worth anything. It was printed in 1845.

And there was something else, another number partly hidden beneath the library card.

“Do you know what this is?” He got up and showed it to Mr. Blake who shrugged.

“They’re not important. This is the one that counts.” Mr. Blake pointed to the Dewey Decimal catalog number.

“Still, I’d like to see the numbers underneath.” Gamache looked round for assistance.

“Maybe we should get Winnie,” said Mr. Blake.

“Good idea.”

Mr. Blake picked up the phone and within minutes the librarian, tiny and suspicious, had arrived. After it was explained she turned to the Chief Inspector. “All right, come with me.”

The three of them went through the corridors, twisting and turning, up some stairs, down others and finally they were in the large back office. Porter Wilson was there as was Elizabeth MacWhirter.

“Hello, Chief Inspector.” Elizabeth came forward and shook hands, as did Porter.

Then, like a surgeon, Winnie bent over the book and with an X-Acto knife pried up the top of the card holder, glued to place a hundred years before.

And below it were the numbers, undamaged, clear as the day they were placed on the dreary first edition.

6-5923

“What does that number mean?” Gamache asked.

There was silence as they took turns looking at it. Finally Winnie answered him.

“I think it’s the old cataloging system, don’t you, Elizabeth?”

“I think you’re right,” said Porter, who clearly didn’t have a clue.

“What old system?” asked the Chief Inspector.

“From the 1800s. We don’t use it anymore,” said Elizabeth, “but back when the Literary and Historical Society was first established this is how they marked items.”

“Go on.”

Elizabeth gave an embarrassed little laugh. “It wasn’t actually much of a system. The Literary and Historical Society was founded in about 1820—”

“1824, actually,” said Mr. Blake. “There’s a charter somewhere around here.”

He searched for it while Elizabeth talked.

“A call went out to the English community at the time to send in memorabilia, whatever people considered of historic importance,” she laughed. “Apparently people took it as an excuse to empty their attics and basements and barns. They were given stuffed lizards, ball gowns, armoirs. Letters, shopping lists. Finally the Society refined its mandate so that it became mostly a library, and even then it was overwhelmed.”

Gamache could imagine mountains of old, leather-bound books and even loose papers.

“As books came in they put on the year it arrived.” She picked up the Scottish grasses volume and pointed. “That’s the number 6 and the other was the number of the book. This one was the five thousandth, nine hundred and twenty-third.”

Gamache was beyond baffled. “Alors, the first number, 6, means the year. But what decade? And was it the five thousandth book that year to arrive, or ever? I’m afraid I’m confused.”

“Ridiculous system,” sniffed Winnie. “Shocking. They obviously had no idea what they were doing.”