Delorme sighed. “Okay. The people who stopped looking were probably those who went on to other interests. They brokered other deals, found new clients, created new weapons. But there are some who can’t do that.”

“Why not?” asked Gamache.

“They don’t have the skills. There are some within the arms community who are bottom feeders. They live off the ideas of others. They’re opportunistic. Mercenary. They’re like grave robbers or treasure hunters. They don’t have to amass the treasure, they just have to find it. And steal it.”

“Surely stealing from an arms dealer can’t be a good idea.”

“No, but if the reward is big enough it might be worth the risk. And in this case, there was no risk. The man who designed the Supergun is dead.”

“Is he?”

Sean Delorme’s head fell to the side, as though the question had shoved him off-kilter. “Are we back there? We told you over breakfast, Gerald Bull took five bullets to the brain. He’s dead.”

“Oui, you did. But suppose Dr. Bull was a great salesman, but not a great designer.”

Delorme opened his mouth to speak, but Gamache held up his hand.

“Hear me out. Isn’t there a certain amount of evidence suggesting just that? That Bull might’ve had the idea, but someone else had to actually design the gun? They’d make the perfect team. Gerald Bull would find a buyer and someone else would draw up the plans.”

Sean Delorme was silent, taking this in. Then he smiled, breaking into a huge, goofy grin.

“You’re kidding, right? Having fun with me?”

Gamache said nothing.

“Come on, there’s no proof of that at all. And who would it be? And please don’t say John Fleming.”

Again, Gamache remained silent, but looked across the room. And Delorme’s smile faded.

“You don’t think…” He glanced over toward Rosenblatt. “But that’s ridiculous. He’s not nearly smart enough.” He lowered his voice. “If he’s still here, it’s for a whole other reason.”

Gamache remembered Delorme’s description of Rosenblatt. A leech. And his description of those who’d spent decades searching for the Supergun. As people who fed on the work of others. Leeches.

“The gun no longer matters, does it?” said Gamache. “Once it was found, anyone looking for the Supergun would have shifted their search. After all, the gun’s being guarded. No one can steal it, or fire it.”

“But someone might build another one,” said Delorme.

“If they had the plans,” said Gamache.

And if the gun was here, the plans might be too.

They’d assumed Laurent had been murdered by someone who knew the gun was there and wanted to keep its location secret. After all, who else would believe his ridiculous story?