“Well?” Gamache asked.

“Highwater was the site of the first Supergun,” said Michael Rosenblatt. He watched Gamache as he spoke. “You’re not surprised.”

Gamache was quiet, waiting to see what Rosenblatt would say, or do, next.

“You went there, didn’t you?” said the scientist, once again fitting the pieces together. “You already knew. So why ask me?”

But his companion remained silent, and once again Rosenblatt put it together.

“It was a test? You wanted to find out if I’d tell you the truth. How did you even know I knew?”

“The redacted pages,” said Armand at last. “You read them but didn’t mention the plural. The censors took out everything, except one reference. Superguns. Everyone else who read those pages saw it. I couldn’t believe you didn’t too. So why wouldn’t you point it out? There was only one answer. Because you already knew, and hoped I hadn’t seen it.”

“Why wouldn’t I want you to know?”

“That’s a good question. Why didn’t you tell us this as soon as you saw the gun in the woods? Didn’t you think it might be important for us to know there’d once been another one, close by?”

Michael Rosenblatt took off his glasses and rubbed his face, then he replaced his glasses and looked at Gamache.

“I actually thought it didn’t matter, but hearing you say it like that, I can see how it might seem suspicious. Not many knew about the other part of Project Babylon,” said Michael Rosenblatt. “The two halves were called Baby Babylon and Big Babylon.”

“Two halves?” asked Gamache. “Of a whole?”

“No, better to call them two parts, but not of a whole. One led to the other. The first was Baby Babylon, the smaller of the two.”

“The one in Highwater.”

“Yes. It was conceived by Gerald Bull through his Space Research Corporation. Baby Babylon was a sort of open secret, like a lot of products in the arms market. Secret enough to be enticing, but out there enough to attract interest.”

“And it did,” said Gamache. “Didn’t it?” he asked when Rosenblatt didn’t answer.

“Of a sort. Baby Babylon was met with ridicule. It was called ‘Baby’ but it was so huge, so ungainly, unlike anything else out there, that it was dismissed as the product of a mind as unstable as the weapon. A fantasist. No credible engineer or physicist thought it could be built. And, if it was, it couldn’t possibly work. Only another unstable mind would commission it.”

“Saddam Hussein,” said Gamache.

“Yes. The fact Saddam was interested just confirmed everyone’s suspicion that the idea was crazy.”

He turned his mug of warm apple cider around in a lazy circle.

“They were wrong,” said Gamache.

“Oh, no. They were right. Baby Babylon didn’t work. It was top-heavy, couldn’t sustain trajectory. With something like that, firing a missile into low orbit and having it travel tens of thousands of miles, if you’re off by one one-thousandth of a degree at launch, you wipe out Paris instead of Moscow on impact. Or Baghdad.”

“Or Bethlehem.”

Rosenblatt didn’t respond to that.

“How did they know it didn’t work?” asked Gamache.

“They fired it.”

Gamache didn’t, or couldn’t, hide his surprise.

“Not into the air,” Rosenblatt hurriedly assured him.

“Then where?” asked Gamache.

“Into the ground.”

Now Gamache looked, and was, confused.

“When you were there, did you happen to notice railway tracks?” the professor asked. “Not the Canadian National ones, but smaller, narrower?”

“Yes. I followed them up the hill.”

“Good. That’s how Bull did it. As with everything else about Project Babylon, it was brilliant in its simplicity. They couldn’t possibly test the missile launcher by actually launching a missile, so they put it on a flatbed on rails at the bottom of a hill and fired it into the ground.”

“What good would that do?” asked Gamache.

“The backward force,” said Rosenblatt. “They measured the degree of incline, the speed and distance traveled, and the depth and trajectory of the hole in the ground. It was so simple it was genius.”

“It doesn’t sound simple to me,” Gamache admitted. Rosenblatt had lost him at “degree of incline.” Gamache considered what he’d heard.

“Wouldn’t it make a lot of noise?” he asked. “So much for secrecy.”