When Thorndyke returned, I informed him of the visit of our two friends, and acquainted him with the sentiments that they had expressed; whereat he smiled with quiet amusement.

“I thought,” he remarked, “that letter would bring Marchmont to our door before long. As to Winwood, I have never met him, but I gather that he is one of those people whom you ‘mustn’t mind.’ In a general way, I object to people who tacitly claim exemption from the ordinary rules of conduct that are held to be binding on their fellows. But, as he promises to give us what the variety artists call ‘an extra turn,’ we will make the best of him and give him a run for his money.”

Here Thorndyke smiled mischievously⁠—I understood the meaning of that smile later in the evening⁠—and asked: “What do you think of the affair yourself?”

“I have given it up,” I answered. “To my paralysed brain, the Blackmore case is like an endless algebraical problem propounded by an insane mathematician.”