Gamache watched as the professor closed his eyes, took a couple of deep breaths, then with one last exhale he turned to his companions.

“I need to find the firing chamber, to see if it’s armed.”

He was all business now.

“It’ll be around here,” he said, walking to the rear of the gun. “Did you open this?”

He pointed to a round metal door, large enough to walk into.

“We tried, but couldn’t make it open,” said Lacoste. “We stopped, afraid we might inadvertently fire it.”

Professor Rosenblatt was nodding. “You wouldn’t have. The firing mechanism is somewhere else. This is the breech. If there’s a missile, it would be in here.”

They watched as the professor ran his hands over the latches and handles and knobs.

“Careful,” warned Beauvoir, but Rosenblatt didn’t respond. He was too focused on the mechanism.

“Do we know for sure he knows what he’s doing?” Lacoste asked Beauvoir.

Before Beauvoir could answer, they saw the professor reach out and grasp a lever. Leaning into it, the elderly man pulled but nothing happened.

“I need help,” he said. “It’s stuck.”

Beauvoir joined him, and between them they pulled and pulled until it gave with such suddenness both men leapt back.

There was a whirring, grinding sound, then a loud hiss.

Gamache tensed. Afraid Rosenblatt had just set it off, but not at all sure what to do if he had.

Then the massive door swung open, like a mouth. Like a maw. Inviting them in.

The four of them stared. Gamache could hear heavy breathing and knew it came from Jean-Guy. Not because the effort had winded him, but because he was staring into his nightmare.

While Gamache was afraid of heights, Beauvoir was terrified of holes. Armand stepped over to him.

“Stay here,” he said. “If the door closes, please open it again.”

Beauvoir didn’t answer, but continued to stare.

“Do you need to write that down?” asked Gamache.

“Huh? Pardon?” said Jean-Guy, coming out of his reverie. “Right. Wait, are you going in there?”

He waved to the opening, where Professor Rosenblatt was already standing.

“I am. And if we need to climb up on the thing?”

“I’ll go,” said Beauvoir, with a smile.

“You’d better.”

Gamache followed Rosenblatt and Lacoste into the chamber.

In the beams of their flashlights, Gamache could see the professor’s face. His eyes. Bright, but not overexcited. He seemed almost calm, in control.

This was his natural environment. The belly of the beast. This was where the little professor belonged.

“Incredible,” Rosenblatt murmured, shaking his head. “No electronics.” He looked back at his companions. “It’s like a Meccano set.”

“But is it armed?” asked Lacoste. She was beginning to get antsy. She’d never suffered from claustrophobia, but then she’d never been crammed into the firing chamber of a giant weapon with two other people before.