“It’s a long trail, covering tens of thousands of miles and hundreds of years. Dom Clément was right to leave. In the archives of the Inquisition there’s a proclamation signed by the Grand Inquisitor himself, ordering an investigation into the Gilbertines.”

“But why?” asked Beauvoir, focusing his attention. It seemed akin to investigating bunnies, or kittens.

“Because of who they sprang from. Gilbert of Sempringham.”

“They were going to be investigated for extreme dullness?” asked Beauvoir.

Frère Sébastien laughed, but not long. “No. For extreme loyalty. It was one of the paradoxes of the Inquisition, that things like extreme devotion and loyalty became suspicious.”

“Why?” asked Beauvoir.

“Because they can’t be controlled. Men who believed strongly in God and were loyal to their abbots and their orders wouldn’t bend to the will of the Inquisition or the inquisitors. They were too strong.”

“So Gilbert’s defense of his archbishop was seen as suspicious?” asked Gamache, trying to follow the labyrinthine logic. “But that was six hundred years before the Inquisition. And he was defending the Church against a secular authority. I’d have thought the Church would consider him a hero, not a suspect. Even centuries later.”

“Six hundred years is nothing to an organization built on events millennia old,” said Sébastien. “And anyone who stands up becomes a target. You should know that, Chief Inspector.”

Gamache gave him a sharp look, but the monk’s face was placid. There seemed no hidden meaning. Or warning.

“If the Gilbertines hadn’t left,” said the Dominican, “they’d have gone the way of the Cathars.”

“And what was that?” asked Beauvoir. But one look at the Chief’s face told him it probably wasn’t to Club Med.

“They were burned alive,” said Frère Sébastien.

“All of them?” asked Beauvoir, his face gray in the dim light.

The monk nodded. “Every man, woman and child.”

“Why?”

“The Church considered them free thinkers, too independent. And gaining in influence. The Cathars became known as the ‘good men.’ And good men are very threatening to not good men.”

“So the Church killed them?”

“After first trying to bring them back into the fold,” said Frère Sébastien.

“Wasn’t Saint Dominic, your founder, the one who insisted the Cathars weren’t real Catholics?” asked Gamache.

Sébastien nodded. “But the order to wipe them out didn’t come until centuries later.” The monk hesitated and when he spoke again his voice was low, but clear. “Many were mutilated first, and sent back to frighten the others, but it only hardened the Cathar resolve. The leaders gave themselves up, in an effort to appease the Church, but it didn’t work. Everyone was killed, even people who just happened to be in the area. Innocents. When one of the soldiers asked how he was supposed to tell them from the Cathars, he was told to kill them all, and let God sort them out.”

Frère Sébastien looked as though he could see it. As though he’d been there. And Gamache wondered which side of the monastery walls this monk from the Congregation for the Doctrine of the Faith would have been on.

“The Inquisition would’ve done that to the Gilbertines?” Beauvoir asked. He no longer looked dazed. The monk had hauled him back from whatever reverie he’d found.

“It’s not a certainty,” said Sébastien, though that seemed more wishful than real. “But Dom Clément was wise to leave. And wise to hide.”

Sébastien took another deep breath.

“This isn’t heresy,” he looked down at the paper in his hands. “It speaks of bananas and the refrain is Non sum pisces.”

Gamache and Beauvoir looked blank.

“I am not a fish,” said the Dominican.

Gamache smiled and Beauvoir looked simply confused.

“So if it isn’t heresy,” said the Chief, “what is it?”

“It’s a singularly beautiful tune. A chant, I think, though not Gregorian and not a plainchant. It uses all the rules, but then adjusts them slightly, as though the old chant was the foundation, and this,” he tapped the page, “a whole new structure.”

He looked up, first at Beauvoir then over to Gamache. His eyes were excited. The smile on his face back to its radiance.

“I think far from being a mockery of Gregorian chant, it’s actually a homage, a tribute. A celebration, even. The composer used the neumes, but in a way I’ve never seen before. There’re so many of them.”