They sat with mugs of tea, warm and comforting, and plates of madeleines Armand had picked up at Sarah's boulangerie as they'd pa.s.sed by.

"What you've found," said Professor Rosenblatt, "is Project Babylon. When we spoke this morning and you described it, I barely believed you. Project Babylon is a tale physicists told to scare each other. It's a Grimms' tale for scientists."

He took a deep breath and tried to cover his discomfort by reaching for another pastry. But his unsteady hand betrayed him.

Gamache couldn't decide if the tremble was caused by fear or excitement.

"What you have is a Supergun. No, not 'a' Supergun, it's 'the' Supergun. The only one of its kind. Within the armaments community it's a sort of legend. For years we'd heard rumors that it'd been built. Some people tried to find it, but gave up. Then the talk died away, as time pa.s.sed."

"When you first saw it," said Gamache, "you whispered, 'He didn't.' Who did you mean?"

Armand leaned forward, forearms on his knees, his large hands forming a sort of bow in front of him. Like a ship plowing through the seas.

"I meant Gerald Bull," said Rosenblatt, and seemed to expect some sort of reaction. A gasp, perhaps. But there was nothing beyond rapt attention.

"Gerald Bull?" Rosenblatt repeated, looking from one to the other to the other.

They shook their heads.

"Look on my works, ye Mighty," said Rosenblatt as he drew his battered leather briefcase toward him. "And despair."

"Oh no," sighed Beauvoir. "Now we have two of them."

"'Ozymandias,'" said Gamache, looking at Jean-Guy with despair. "The professor was quoting a sonnet by Sh.e.l.ley-"

"-of course he was."

"-that speaks of arrogance, of hubris. A king who thought his achievements would stand for thousands of years, but all that remained of him was a broken statue in the desert."

"And yet he was finally immortalized," said Rosenblatt. "Not because of his power, but because of a poem."

Beauvoir looked about to say something smart-a.s.s, but stopped. And thought.

"Who was Gerald Bull?" he finally asked.

Professor Rosenblatt had unbuckled the briefcase and, after sorting through the contents, brought out some papers.

"I found these in my files after we spoke. I thought they might be needed."

He put the papers, held together by a staple, on the coffee table.

"This is Dr. Bull."

Isabelle Lacoste picked them up. What the professor had brought was yellowed and typewritten. There was also a grainy black-and-white photograph of a man in a suit and narrow tie, looking put upon.

"He was an armaments engineer," said Rosenblatt. "Depending on who you speak to, Dr. Bull was either a visionary or an amoral arms dealer. Either way, he was a brilliant designer."

"He made that thing in the woods?" asked Lacoste.

"I think so, yes. I think it was part of what he called Project Babylon. His goal was to design and build a gun so powerful it could launch a missile into low Earth orbit, like a satellite. From there it would travel thousands of miles to its target."

"But don't those exist?" asked Beauvoir. "ICBMs?"

"Yes, but the Supergun is different," said Rosenblatt.

"The Meccano set," said Lacoste. "No electronics."

"Exactly." The professor beamed at her. "No computer guidance systems. Nothing that depends on software or even electricity. Just good old-fashioned armaments, not that far off the artillery used in the First World War."

"But why was that such an achievement?" asked Gamache. "It sounds like a step back, not forward. As Inspector Beauvoir says, if there're ICBMs that can send nuclear warheads thousands of miles accurately, why would anyone want or need Gerald Bull's Supergun?"

"Think about it," said Rosenblatt.

They did, but nothing came to mind.

"You're too mired in the present, in thinking that newer must be better," he said. "But part of Gerald Bull's genius was recognizing that ancient design could not only work, but in some cases, work better."

"Did he also build a giant slingshot?" asked Beauvoir. "Should we be looking for one of those?"

"Think," said Rosenblatt.

Gamache thought, and then he looked around their home. At the useless smartphone on the desk in the study. At the dial-up connection that barely worked.

He looked at the crackling fireplace, feeling its heat, and he thought about the woodstove in the kitchen. In Clara's kitchen. In Myrna's bookstore.

If the power went out they'd still have warmth and light. They could still cook. No thanks to modern technology. That would be rendered useless, but they'd have power because of old, even ancient, tools. Woodstoves. Wells.

Three Pines might be primitive in many ways, but unlike the outside world, it could survive a very long time without power. And that itself was powerful.

"The weapon needs no power source," said Gamache slowly. Coming to the realization, and the implication. "It can send a missile into orbit without even a battery."

Professor Rosenblatt was nodding. "That's it. The brilliance and the nightmare."

"Why nightmare?" asked Beauvoir.

"Because Dr. Bull's Supergun meant any terrorist cell, any extremist, any crazy dictator could become an international threat," said the scientist. "They didn't need technology, or scientists, or even electricity. All they'd need was the Supergun."

He let that sink in, and as it did even the cheery fireplace couldn't take the chill out of the room, or wipe the alarm from their faces.

"But maybe he didn't do it," said Lacoste. "Maybe he wasn't successful. Maybe Bull abandoned it because it doesn't work."

"No," said Professor Rosenblatt. "He abandoned it because he was killed."

They stared at him.

"How?" asked Gamache.

"He was murdered in 1990. Some describe it as an a.s.sa.s.sination. He was living in Brussels at the time. Five bullets to the head."

"Professional," said Lacoste.

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 a.s.sumption 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 ma.s.s 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 cla.s.sicist. 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 cla.s.ses as a child. Beauvoir shook his head impatiently. And Gamache just stared in a way the professor found disconcerting.

"The Wh.o.r.e 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 Wh.o.r.e 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 amus.e.m.e.nt. "Oh, come on," he said, his handsome lean face breaking into deep lines of laughter. "Really?"

He looked at them, his eyes finally resting on the elderly scientist.

"Are you seriously saying that thing in the forest is the devil?"

"I'm not saying that, but you asked about the Wh.o.r.e of Babylon and that's the answer. You can look it up yourselves or ask any biblical scholar. There're all sorts of interpretations about what the beast and the seven heads represent, but most come to the same conclusion. She's heading for Armageddon."

"As was Gerald Bull," said Lacoste. "In building the Supergun he was courting the end of the world."

"Well now," said Rosenblatt. He looked down at his feet, then up at her. "The community is divided on that. Many, probably most, think Dr. Bull was a mercenary. An arms dealer. A one-stop shop. He'd design, build and sell any weapon to the highest bidder."

"And the others?" asked Gamache. "The minority?"

"They think Dr. Bull was a hero. That he was very clear about why he was building the Supergun, and who he was making it for. They believe he carved the beast on it as a sort of gesture. Like pilots in the Second World War often painted frightening images on their planes."

"He called it Project Babylon," said Gamache. "Why?"

"Who was the devil in the late 1980s?" Rosenblatt asked.

"The Soviet Union," said Lacoste, remembering her history.

"The Cold War was waning," said Gamache. "Yeltsin and President Gorbachev were bringing in glasnost."

"Exactly," said Rosenblatt. "But there was someone else. An ally who was fast becoming an enemy. A wolf in sheep's clothing, to use another biblical image."

"Babylon?" said Gamache. "Are you saying Gerald Bull built that thing for Saddam Hussein?"

He didn't even try to keep the incredulity out of his voice, and he could only imagine the look on Jean-Guy's face.

"You don't believe it?" asked Professor Rosenblatt. The words fell into the silence in the room and drifted into the fireplace, to be burned.

"Would you?" asked Isabelle Lacoste, regarding the elderly man and wondering just how crazy he might be. The gun itself was hard enough to swallow, but she could at least see it, touch it. She knew it was real. But this was a step too far.

"I don't suppose it really matters if you believe it or not," said Rosenblatt, gathering up his papers. "You asked me here to tell you what I know. That's what I know."