Rosenblatt nodded. “The killers were never caught.”

Gamache’s eyes narrowed in concentration.

“I seem to remember this,” he said. “Gerald Bull was a Quebecker—”

“Actually, he was born in Ontario and studied at Queens University. It’s all in there.” Rosenblatt waved at the papers he’d brought them. “But he did much of his work here in Quebec. At least, at first.”

“Did you know him?” asked Gamache.

“Not really. He was at McGill for a short while. Considered a bit of a crank. Difficult.”

“Unlike physicists?” asked Gamache, and saw Rosenblatt smile.

“I’m afraid I’m not brilliant enough to be difficult,” he said. “That’s reserved for geniuses. I was just an academic, teaching students about trajectory. Or trying to. When sophisticated systems came in, students realized they didn’t really have to know these things. Computer programs would do it all for them. I might as well have been using a slide rule and an abacus.”

“Dr. Bull never came to you for advice?” Gamache prodded.

Now Rosenblatt laughed outright. “Advice? Gerald Bull? No. And he wouldn’t have come to me anyway. I was much too lowly.”

The two men regarded each other before Gamache finally smiled and dropped his eyes. But Michael Rosenblatt took warning, and wondered if he might have just overdone it.

“The chatter after he’d died was that Bull had in fact built the Supergun,” said Rosenblatt. “And it was ready to be tested. But no one knew where it was. And it was all just gossip. People like drama but no one really believes it.”

“Why was he killed?” Beauvoir asked.

“No one knows for sure, of course,” said Rosenblatt. “The assumption was he was killed to stop him from building the gun.”

“By the waters of Babylon,” Gamache quoted, his eyes on the elderly scientist, “we sat down and wept. There’s more to tell, Professor. We’ll find out eventually, you know. Why was that etching, the beast, carved into the gun? Why did Gerald Bull put it there? And why that quote?”

Professor Rosenblatt looked around in a glance that would have been ludicrously furtive had they not been talking about a gun whose very existence had killed at least two people. Its maker and Laurent. And whose intent was to kill far more.

Michael Rosenblatt realized, too late, that he had vastly underestimated all three of them. And certainly Gamache. It was true, they would find out eventually.

But perhaps, he thought, his mind racing, not everything.

He might as well tell them. But perhaps, he thought, not everything.

“Gerald Bull was a Renaissance man,” he said, and heard Beauvoir snort. He turned to the Inspector. “The Renaissance created amazing works of art, of innovation. But it was also a brutal time. I’m not unaware of the fact that this is a weapon.”

“Of mass destruction,” said Gamache, who was also having none of this glorification of an arms designer, an arms dealer.

Professor Rosenblatt studied him to see if there was any other agenda, anything else behind the exact words Gamache had just chosen. But there didn’t seem to be.

“True. But he was also a classicist. A man who loved music and art and history. Dr. Bull knew perfectly well what he was building. Stories circulated within the armaments community that he’d not only built the Supergun, but carved a seven-headed beast on it, as a reference to the Book of Revelation.”

He looked at them. Isabelle Lacoste was thinking, trying to remember her Bible classes as a child. Beauvoir shook his head impatiently. And Gamache just stared in a way the professor found disconcerting.

“The Whore of Babylon?” said Rosenblatt.

“Just tell us,” said Beauvoir, his patience at an end.

The professor took out his iPhone, punched at the screen, then put it on the table. Beside the golden madeleines glowed the image of a monster rearing up with seven heads on long serpentine necks springing from the body.

And riding the monster was a woman, not looking out to where the beast was taking her, but staring back at whoever was staring at her.

“Who’s the Whore of Babylon supposed to be?” Beauvoir demanded.

Professor Rosenblatt was about to answer, but then turned to Gamache. “I think you know.”

Gamache hadn’t taken his eyes off the image. “The Antichrist.”

Beauvoir sputtered in amusement. “Oh, come on,” he said, his handsome lean face breaking into deep lines of laughter. “Really?”