A period of silence followed, during which the three men looked at each other. The Professor broke it as last, with a direct question. “You’ve no clue so far?” “None!” answered Blick. “You’ll have to hark back,” said the Professor. “London! Get at some of Markenmore’s recent doings there. Now, as I came through London from Cambridge yesterday, I made it in my way to call at Markenmore’s office in Folgrave Court to make a few enquiries. Markenmore’s head clerk gave me some information. He remembered my assistant, Mr. Carter, calling. He himself saw Carter deliver to Markenmore my sealed letter; he saw Markenmore give Carter a receipt for it, which Carter sent on to me by post. I have it in my pocket now. The head clerk says that as soon as Carter had gone, he saw Markenmore break the seals of my letter, draw two papers from it and read them. Markenmore, the moment he had finished them, went into the telephone-box in the hall of their building and presumably rang somebody up. Within half an hour a man came who was an absolute stranger to the head clerk; he is positive that this man had never been there before, but he remembers him well—a foreigner, by appearance—and can give you an accurate description of him. Now, the clerk saw Markenmore produce my sealed letter—unsealed, of course, I mean—and show this strange man the two papers which it contained. A few minutes later they went out together. Now, who is that man? You’ll have to find him.” The Chief Constable looked at Blick. “This,” he said, “seems like shifting the scene of your operations.” But Blick looked at the Professor. “What description—of this stranger—did Markenmore’s clerk give you?” he asked. “Dark, swarthy, middle-sized, middle-aged man—very well dressed,” responded the Professor promptly. “The sort of man, he said, you see much of in financial circles. Some sort of a foreign Jew—in the clerk’s opinion.” “Had such a man come into these parts, he must have been seen,” said Blick. “I’ve made minute enquiries about the recent presence of strangers at all the railway stations——” “There are other ways of transport than railways,” observed the Professor. “But, anyway, here’s one thing certain—Markenmore showed the formula and my opinion on it to this man!” Blick walked about the room awhile, in his favourite attitude—head down and hands in pockets. He turned at last to the Chief Constable. “Well, I’m going back to Markenmore,” he said. “There are certain things to see to, there. Afterwards——” “We must have more talk,” responded the Chief Constable. “As you say—afterwards.” The Professor rose and picked up his hat and walking-stick. “I am going to stay at the Mitre here for a day or two,” he said. “So, if you want me, you’ll know where to find me. But while I am here, I should like to see the scene of all this mystery, and if you’re going out there, Sergeant, I’ll go with you, if I may.” “Great pleasure, sir,” replied Blick.