Armand was either staring after the scientist or into space. He seemed to make up his mind. Getting up, he walked to the bar, and placed a phone call, turning his back to the room as he spoke. Then he returned to the table, wedged snug into the corner.

Clara got up, followed by Myrna, and slipped into seats on either side of him.

“I think I’ve found something interesting,” said Clara. “But I’m not sure.”

“She’s sure,” said Myrna.

“Tell me,” said Armand, turning his full and considerable attention to her.

*   *   *

“Take a seat.” Isabelle Lacoste indicated the conference table in the Incident Room. Mary Fraser and Sean Delorme joined Inspector Beauvoir, who was already there.

“Project Babylon wasn’t one missile launcher,” said Beauvoir without preamble. “It was two. Why didn’t you tell us this before?”

Gamache had called them from the bistro after Professor Rosenblatt confirmed there were two guns, christened with the unlikely names Baby Babylon and Big Babylon.

Mary Fraser was perfectly contained, in her drab way. Isabelle Lacoste had the impression that the middle-aged woman should have a ball of knitting in her lap like some benign presence, there to calm and soothe infants who were acting out.

“Is it?” asked Mary Fraser.

Isabelle Lacoste leaned slightly forward and, lowering her voice, she said, “Highwater.”

It was like throwing a boulder into a small pond. Everything changed.

“But Baby Babylon didn’t work—” said Mary Fraser.

“Mary,” Sean Delorme interrupted.

“They already know, Sean.”

Now it was his turn to stare at his colleague. “You knew they’d found out about Highwater and you didn’t tell me?”

“I forgot.”

“That’s not possible,” he said, examining her.

“This isn’t the time to discuss it.”

Her words mirrored their exchange when they’d first arrived in Three Pines. Their little tiff over driving. Then it had been almost endearing, now it was chilling. And by the look on Sean Delorme’s face, he felt it too. With one more quick glance at his partner, he turned back to the Sûreté investigators.

“Have you been there?”

“Up the hill, following the tracks?” said Beauvoir.

Delorme shifted in his chair, took a breath, and nodded.

Mary Fraser, however, sat absolutely still, composed. Frozen.

“We knew about the one in Highwater, but not the other,” she admitted.

“You went there,” said Lacoste.

“Yes. To confirm that the pieces were still there and hadn’t also been made to work. But I admit, Big Babylon came as a genuine shock.”

Neither Lacoste nor Beauvoir were swallowing this whole. There was very little “genuine” about these two.

“Why didn’t you tell us about Highwater?” said Lacoste.

“That a giant gun had been built, with our knowledge, on the border with the U.S. thirty-five years ago?” asked Mary Fraser. “Not exactly dinner table conversation.”

“This isn’t a dinner table,” Lacoste snapped. “This is a murder investigation. Multiple murders, and you had valuable information.”

“We had nothing,” said Mary Fraser. “How does it help find your killer to know about a long-abandoned and failed experiment?”

Jean-Guy reached into the evidence box and brought out the pen set and the bookends and placed them on the table in front of him, then, without a word, Isabelle Lacoste picked them up, manipulating them.

The CSIS agents watched with mild curiosity that became astonishment as they realized what she was doing.

After the final piece clicked into place, she put it on the table in front of Mary Fraser. It was Sean Delorme who picked it up and examined it.

“The firing mechanism?” he finally asked.

“Oui,” said Lacoste. “In case you didn’t know, that”—she thrust her finger toward the assembled piece—“is a pretty good representation of a homicide investigation. All sorts of apparently unrelated and unimportant pieces come together to form something lethal. But we can’t solve a case if people are keeping information from us.”

“Like a big goddamned gun on the top of a hill,” said Beauvoir. “The baby brother of the one in the woods.”

Mary Fraser took this in but seemed unmoved, and Lacoste suspected it was because to her secrets were as valuable as information. She was not designed to give up either.