Mr. Ingles shrugged.

“Oh, signs⁠—yes, certainly. And once I found a man who would talk, a brilliant young Chinese chemist who was a protégé of Li Chang Yen’s. He came to me one day, this chemist, and I could see that he was on the verge of a nervous breakdown. He hinted to me of experiments on which he’d been engaged in Li Chang Yen’s palace under the mandarin’s direction⁠—experiments on coolies in which the most revolting disregard for human life and suffering had been shown. His nerve had completely broken, and he was in the most pitiable state of terror. I put him to bed in a top room of my own house, intending to question him the next day⁠—and that, of course, was stupid of me.”

“How did they get him?” demanded Poirot.

“That I shall never know. I woke that night to find my house in flames, and was lucky to escape with my life. Investigation showed that a fire of amazing intensity had broken out on the top floor, and the remains of my young chemist friend were charred to a cinder.”