“Oh mon Dieu!”

“You mustn’t tell anyone, Thomas. Not even Édith. Especially Édith.” He paused. “Unless you want your brother …”

Executed. Or at least in prison.

“And now I’m party to it,” said Thomas.

“You opened the carpet. I never meant that to happen.”

“How will you dispose of the body?”

“That’s a secret. Unless you want to help me.”

Thomas was silent. He had two choices. One was to go to the police at once, and betray his brother. The other was not to betray him. If the latter, then he wanted to be sure the body was never found. The poor girl was dead anyway.

He weighed the options.

“I never knew what was in the carpet. You understand? If you’re ever caught and it’s discovered I brought the carpet up here, I had no idea what was in it.”

“That was always my plan.”

“How will you hide her?”

Luc glanced out of the window. Dusk was already falling.

“You’ll see soon enough,” he said.

It had been a year ago, Luc explained, that he’d been in the privy and heard a sound of rock and earth falling just behind him. Investigating afterward, he’d discovered that there had been a little landslide on the slope. And as he probed further, he realized that a small fissure, a few inches wide, had appeared. When he pushed a stick through, he found a cavity. The rock was quite soft. Widening the fissure, he was soon able to step into the cavity, and the next thing he knew, he was in a tunnel.

“It wasn’t a great surprise. You know the hill of Montmartre is riddled with old gypsum mines.”

“So did you explore?”

“Oh yes. There’s a network of tunnels in there.” He nodded thoughtfully. So I rebuilt the privy with a shed beside it. The back of the shed slides open. The opening’s just behind it.”

“Did you tell anyone?”

“Not a soul, except you.”

Although the little garden wasn’t overlooked, Luc waited until darkness had fallen before he led Thomas out to the privy. He gave Thomas a covered lamp to carry. While Thomas waited, Luc entered the little shed beside it, and Thomas heard a wooden partition slide open.

“Bring the lamp,” Luc whispered. Thomas stepped into the shed and felt Luc’s hand guiding him through into the tunnel. “Turn left,” Luc whispered, “and walk twenty paces. Then you can uncover the lamp.” The surface under his feet felt stony.

When he uncovered the lamp, Thomas saw that he was in a high passage, about six feet wide, that led away into the distance. The walls were quite smooth and it was dry.

“Leave the lamp here,” Luc said. “Nobody can see the light from outside. We’ll go back for the girl now.”

She clearly had been in her early twenties. A fair-haired girl. She’d been hit in the face, but that hadn’t killed her. More likely the blow to the back of her head had done that. She must have fallen hard against something. Thomas wanted to ask, “How did it happen?” but he decided the less he knew the better.