"A GENTLEMAN to see you, Doctor." From across the common a clock sounded the half-hour. "Ten-thirty!" I said. "A late visitor. Show him up, if you please." I pushed my writing aside and tilted the lamp-shade, as footsteps sounded on the landing. The next moment I had jumped to my feet, for a tall, lean man, with his square-cut, clean-shaven face sun-baked to the hue of coffee, entered and extended both hands, with a cry: "Good old Petrie! Didn't expect me, I'll swear!" It was Nayland Smith—whom I had thought to be in Burma! "Smith," I said, and gripped his hands hard, "this is a delightful surprise! Whatever—however—" "Excuse me, Petrie!" he broke in. "Don't put it down to the sun!" And he put out the lamp, plunging the room into darkness. I was too surprised to speak. "No doubt you will think me mad," he continued, and, dimly, I could see him at the window, peering out into the road, "but before you are many hours older you will know that I have good reason to be cautious. Ah, nothing suspicious! Perhaps I am first this time." And, stepping back to the writing-table he relighted the lamp.