“While the scientists say it’s alpha waves, the Church calls it ‘the beautiful mystery.’”

“The mystery being?”

“Why these chants, more than any other church music, are so powerful. Since I’m a monk I think I’ll go with the theory they’re the voice of God. Though there’s a third possibility,” the Dominican admitted. “I was at dinner a few weeks ago with a colleague and he has a theory that all tenors are idiots. Something to do with their brain pans and the vibration of the sound waves.”

Gamache laughed. “Does he know you’re a tenor?”

“He’s my boss, and he sure suspects I’m an idiot. And he might be right. But what a glorious way to go. Singing myself into stupidity. Maybe Gregorian chants have the same effect. Make us all into happy morons. Scrambling our brains as we sing the chants. Forgetting our cares and worries. Letting the world slip away.” The younger man closed his eyes and seemed to go somewhere else. And then, just as quickly, he came back. Opening his eyes he looked at Gamache, and smiled. “Bliss.”

“Ecstasy,” said Gamache.

“Exactly.”

“But for monks it’s not just music,” said Gamache. “There’s also prayer. The chants are prayers. It’s a potent combination. Both mind altering, in their way.”

When the monk didn’t say anything, Gamache continued.

“I’ve sat here for a number of services now and watched the monks. To a man they go into a sort of reverie when singing the chants. Or even just listening to them. You did it just now, just thinking about the chants.”

“Meaning?”

“I’ve seen that look before, you know. On the faces of drug addicts.”

That seemed to shock Frère Sébastien, who stared at Gamache. “Are you suggesting we’re addicted?”

“I’m telling you what I’ve observed.”

The Dominican got to his feet. “What you might have missed is the genuine faith of these men. Their commitment to God, to the perfection of the heart. You diminish it, sir, when you describe their solemn commitment as simply an addiction. You turn the chants into a disease. Something that weakens us, rather than strengthens. To characterize Saint-Gilbert-Entre-les-Loups as no better than a crack den is absurd.”

He walked away, his feet, unlike the other slippered monks, rapping against the slate floor.

Gamache knew he might have gone too far. But in doing so he’d hit a nerve.

*   *   *

Frère Sébastien stood in the shadows. After stomping off he’d gone to the far door, opened it, then let it swing shut. Without going through it.

He’d stood in the crook of the church, the corner, and watched the Chief Inspector. Gamache had sat in the hard pew for a minute or so. Most people, the monk knew, had difficulty sitting still for thirty seconds. This quiet man seemed capable of sitting in the stillness for as long as he wanted.

Then the Chief Inspector had gotten up and without genuflecting, had left the Blessed Chapel. He’d walked to the door that led down the long corridor, to a locked door and the quiet young monk with the remarkable voice. Frère Luc.

Leaving Frère Sébastien alone in the Blessed Chapel.

It was now or never, the Dominican realized.

He started a slow, but steady search of the room. At the empty lectern he laid his hand on the worn wood, then continued the methodical search. Once he was satisfied the chapel was keeping no secrets, he stole down the corridor and into the prior’s office, which the police officers had made their headquarters. There he rifled drawers, looked in files, opened folders. He looked under the desk, behind the door.

The Dominican turned on the computer, knowing what he was looking for would never be there. But he was determined not to have come this far and leave a stone unturned. Unlike the Gilbertines, who seemed satisfied to stay in the sixteenth century, Frère Sébastien was a child of his times. He could never do his job if he didn’t know and admire technology. From planes, to cell phones, to laptops.

They were his tools, as crucial as a cross and holy water.

He scanned the files, though there wasn’t much to see. The laptop wasn’t connected, the satellite hookup too finicky. But before he could turn it off he heard a familiar whirr.

The DVD had kicked in.

Curious, the Dominican clicked and an image appeared. A video. The sound was turned down, which suited him. Besides, the images told the whole story.

He watched with growing dismay, repulsed by what he saw but unable to look away. Until the screen went dead.