“Gerald Bull became an arms dealer,” said Gamache. “But not, perhaps, an arms designer.”

“That explains why Project Babylon was built here,” said Beauvoir. “Because Guillaume Couture was here.”

“He built the prototype close to home,” said Lacoste. “Where he could oversee it, but no one else could. In the middle of a Québec forest, where the Iranians, the Israelis, the Iraqis, our own people would never think to look. A gun that doesn’t exist in a village that doesn’t exist.”

“The last place on earth,” said Beauvoir. “Three Pines.”

“And no one guessed that Gerald Bull wasn’t the creator of Project Babylon?” asked Cohen.

“Why would they?” asked Chief Inspector Lacoste. “And who would care? As long as he delivered.”

“And when he’s murdered, Couture gets scared,” said Beauvoir. “He hides the plans, or maybe destroys them, and goes to ground. Retires to his tomatoes and peppers, and tries to forget about the thing in the woods.”

“It was covered with camouflage netting,” said Gamache. “An effort had been made to hide it. And the firing pin was removed. Who else but the designer could do that? Did you find the firing pin in Antoinette’s home?”

“No, though to be fair, we weren’t looking,” said Beauvoir. “We’ll go back and have another look.”

“If it was there, the killer probably took it,” said Gamache. “But worth a look.”

“I’ll double the guard on the gun,” said Lacoste, and headed to the telephone in the study.

The lights suddenly went on, full force, and Armand looked over at Reine-Marie, who was standing by the switch, then she returned to the table.

“Well, that killed the mood,” said Jean-Guy.

“I wanted a clearer look at this picture,” she said, bending over it.

“Do you recognize someone, Madame Gamache?” Adam Cohen asked.

“No, not the people, but the place looks familiar. Armand?”

The three men in the grainy enlargement were standing at the top of a very long tunnel that sloped downward. The walls appeared to be metal, with strips of more metal shooting down the sides and ceiling. Huge pot lights were attached to the top.

“I don’t think this’s a tunnel,” she said. “I think they’re standing at the top of a long cylinder.”

“The mouth of a gun, perhaps,” said Gamache.

“It would have to be a pretty big gun.”

“Well, we have a pretty big gun,” he said.

“I don’t think it’s a gun,” said Beauvoir, leaning over Madame Gamache’s shoulder. “It actually looks more like a stairway.”

“Or an escalator,” said Armand.

It did look vaguely familiar. A metro stop? An airport? It could be anywhere.

“Oh, this’s killing me,” said Reine-Marie.

“Probably doesn’t matter,” said Armand. “The picture was obviously taken years ago.”

“What would happen if another one of those guns was built?” Reine-Marie asked.