“Who designed Project Babylon?” asked Gamache.

Rosenblatt nodded toward the photograph. “You already know.”

“I need you to confirm it.”

Even now, even when worn down and cornered, Gamache could see the elderly scientist twisting, so deep was the instinct and perhaps the training to evade.

“The plans may have been found,” Gamache said quietly.

“Ahh,” said Rosenblatt. The sound slipped out of him, like a long tail on a sigh.

He nodded a few times, carrying on some internal conversation. A debate. An argument. And then he spoke.

“Guillaume Couture designed Project Babylon. I suspect Gerald Bull conceived of the idea, but he needed someone smarter than himself to actually figure out how to do it. So he found Dr. Couture ferreting away in the engineering department of McGill. Couture became Bull’s chief designer and silent partner.”

Now that he’d started, Professor Rosenblatt couldn’t seem to stop talking. It was such a stream of information and confidences that Gamache found himself wary. Not sure if this was the truth, half-truths, or a blockade of lies.

Though it fit with their own conclusions. Perhaps a bit too well.

“Gerald Bull essentially committed suicide when he put himself forward as the sole designer of Project Babylon,” said Rosenblatt. “He was killed to stop him. No one knew about Guillaume Couture.”

“Except you,” said Beauvoir.

“Oh, I didn’t know. Not until much later. All that research on Gerald Bull, it didn’t fit, until I factored in someone else. Someone smarter.”

“Do you think Dr. Couture would have kept the plans?” Beauvoir asked. “After all, they’re what got his boss killed.”

“It was his life’s work,” said Rosenblatt. “Guillaume was a nice man, in many ways a gentle man. But he was unbothered by a conscience. He had no imagination. No, that’s probably unfair. He was myopic. Shortsighted. He only saw the challenge, the scheme. He didn’t look beyond that, to what his plans would actually do.”

“So what does that mean?” Beauvoir demanded. “Would he have kept the plans or not?”

“I think so,” said Rosenblatt. “They were the work of a lifetime. Without doubt the highlight of his career.” He considered for a moment. “You say the woman killed last night was his niece?”

“She lived in his home,” said Gamache.

In the background, the clock on the bistro mantel struck the hour. Midnight.

“And you didn’t find the plans?” Rosenblatt asked.

Gamache shook his head and in the silence the clock continued to sound. One measured stroke after another.

“You think the killer has the designs for Project Babylon,” said Rosenblatt.

“I think it’s possible. We have to assume he found them,” said Gamache.

The clock struck one last time, then stopped.

Michael Rosenblatt looked at it, then back at Gamache.

“The chimes at midnight, Chief Inspector,” he said quietly. “It’s later than we thought.”