“They’re trained commandos, Remi. Skulking is what they do.”

Sam scanned the grounds, taking his time, looking into shadows and darkened doorways, but seeing no one else. “Great Christmas present idea,” Sam said. “A night-vision monocular.”

“My pleasure.”

“I don’t see anyone else. Wait . . .”

The man under the eaves moved now, turning again to look over his shoulder. On the sleeve of his jacket was a patch, and on his belt a flashlight and key ring.

“I’m happy to report I’m wrong,” Sam murmured. “It’s a guard. Still, it would probably be best if we didn’t get caught sneaking about a French national monument in the dead of night.”

“True.”

“When I say go, slowly move into the tunnel and stop about halfway. Don’t go into the courtyard. And be ready to freeze.”

“Right.”

Sam watched the guard through the monocular until he looked away again. “Go.”

Hunched over, Remi hurried into the corner, then along the wall and into the arch. Sam kept watching. It took another two minutes, but finally the man moved again and Sam was able to join Remi.

“My heart’s pounding,” she admitted.

“The joy of adrenaline.”

They took a moment to catch their breath, then crept down the tunnel to the mouth of the courtyard, stopping just short of a two-inch-high step.

To the left of the door was a short wall and a wooden bench. To the right, a set of stone steps bordered by a wrought-iron handrail rose alongside the courtyard’s inner wall then turned left and ascended to a turret, where it branched off into a walkway that wrapped around the courtyard. Sam and Remi scanned the walkway, pausing on each rectangular door or window, looking for movement. They saw nothing.

They scooted forward, gave the courtyard and walkway one more look, and were preparing to move when Sam saw, set back in the shadows, another archway beneath the steps.

Nothing moved. Aside from the pattering rain, all was quiet.

Eyes scanning the courtyard, Sam leaned in and whispered in Remi’s ear, “When I say go, head straight up the steps and into the turret. I’ll be right—”

Behind them a beam of light filled the tunnel.

“Remi, go!”

Like a sprinter coming off the blocks, Remi dashed out and started up the steps, taking them two at a time. Sam dropped to his belly and went still. The flashlight panned through the tunnel, then back out again, then went dark. Sam crawled over the step into the courtyard, then rose to his feet and joined Remi in the turret.

“Did he see us?”

“We’ll know shortly.”

They waited for a minute, then two, half-expecting to see the guard walk through the arch, but he didn’t appear.

Sam looked around the darkened interior of the turret. “Are we in the right one?”

The brochure map had identified several entrances to the oubliette level, one of which was in this turret. “Yes, the next landing down, I think,” Remi said, nodding at the spiral steps; another set led upward to the battlements.

They started down the steps, Remi in the lead. On the next landing they found a wooden trapdoor in the floor, secured to the stone lip by a padlocked latch. From his waistband Sam pulled a miniature crowbar. Given the predominantly stone construction of the château and recalling Müller’s words about his brother finding the bottles “tucked away in a cranny,” they’d guessed the tool would come in handy.

While the padlock looked new, the latch itself was anything but, having turned black and flaky by years of exposure to the salt air. Remi pointed her LED microlight at the latch, but Sam stopped her from turning it on. “Let’s wait until we’re out of sight.”

It took thirty seconds of gentle work with the crowbar’s tip to wriggle the latch free of the wood. Sam lifted the hatch, revealing a wooden ladder dropping into a dark shaft.

“Better let me test it,” Remi said.

She sat down, slid her legs into the hole, and started downward. Ten seconds later she whispered up, “Okay. It’s about twelve feet. Go easy. It’s bolted into the stone, but the whole thing looks as old as the latch.”

Sam climbed in, ducked down on the second rung, and shut the hatch behind him, leaving a gap wide enough for his fingers, which he used to flip the latch back into place; with luck, a passing guard wouldn’t notice the tampering.

In complete darkness and working by feel alone, Sam started downward. The ladder creaked and shifted, the bolts rasping inside their stone holes. He froze. He held his breath for a ten count, then began moving again.

With a splintering crack, the rung parted beneath his lowermost foot. He lurched downward. He clamped his hands on the uprights, arresting his fall, but the sudden shift of his weight was too much for the ladder, which twisted sideways. With a shriek and a pop, the bolts gave way and Sam felt himself falling. He braced himself just before impact, slamming into the stone floor back first.

“Sam!” Remi whispered, rushing over and kneeling down.

Sam groaned, blinked rapidly, then pushed himself up onto his elbows.

“Are you okay?” she asked.

“I think so. Just bruised my pride a bit.”

“And your tailbone.”

She helped him to his feet.

Before them the ladder lay in a heap. The uprights were twisted away from one another, the rungs jutting at crazy angles.

“Well,” Remi said, “at least now we know how we’re not getting out of here.”

“Always a bright side,” Sam agreed.

Remi clicked on her LED and they looked around. Behind them was a stone wall; ahead, a passageway barely taller than Sam stretched into the darkness. Unlike the fort’s outer walls, the stones here were dark gray and rough-hewn, showing chisel marks that were four hundred-plus years old. This was the upper dungeon level; there was one more below them, and below that, the oubliettes—“the realm of the forgotten.”

Remi clicked off her LED. Hand in hand, they started down the passage.

When they’d gone twenty paces, Sam clicked on his LED, looked around, shut it off again. He’d seen no end to the passage. They kept going. After another twenty paces, he felt Remi’s hand squeeze on his.

“I heard an echo,” she whispered. “To the left.”

Sam clicked on the LED, revealing a tunnel containing a dozen cells, six to a wall. For safety purposes the barred steel doors had been removed. They stepped into the nearest cell and looked around.

While these tunnels were gloomy in their own right, Sam and Remi found the tiny coalpit-dark cells a nightmare. The château’s guides reportedly divided tour groups into threes and fours, then shut off the lights and had everyone stand in silence for thirty seconds. Though Sam and Remi had found themselves in similar situations before—most recently in Rum Cay—Château d’If’s cells evoked a unique sense of dread, as though they were sharing the space with still-imprisoned ghosts.

“Enough of this,” Sam said, and stepped back into the main passage.

They found the next tunnel farther down the passageway on their right. This one was slightly longer and contained twenty cells. Moving more quickly now, they repeated the process, passing cell tunnel after cell tunnel until they reached the end of the passageway, where they found a wooden door. It was closed but had neither latch nor lock. Beside the door a placard said in French, DO NOT ENTER. AUTHORIZED PERSONNEL ONLY.

“Why no lock?” Remi wondered aloud.

“Probably removed so wayward tourists can’t accidentally lock themselves in places they shouldn’t be.”

He stuck his finger through the latch hole and gently pulled. The door swung open an inch. The hinges creaked. He stopped, took a breath, then pulled the door the rest of the way open.

Remi squeezed through the gap, then he followed, easing the door shut behind them. They stood still for a few moments, listening, then Remi cupped her hands around her LED and clicked it on. They were standing on a narrow, four-by-four-foot landing. To the right of the door was a ledge; at their backs, another cylindrical stairwell, this one leading only downward. Together they peeked over the ledge.