took the number as the cab went off. Corder ought to have collared him then and there, I think, but he was in a difficult position. It would have endangered the case he was on, which is very important; and besides, he didn't realise how much we wanted him for, having only been brought in as an assistant at the tail of our bond case. Still less did he guess--any more than myself--what I was going to hear at the Admiralty office." "At any rate," interrupted Hewitt, "you've got the number of the cab?" "Here it is," Plummer answered, "and I've already set a man to get hold of the cabman. You'd better note the number--92,873." Hewitt duly noted the number, and advised me to do the same, in case I should chance to meet the cab during the afternoon; and as we neared our destination Plummer gave us the rest of the case in outline. "In the office," he said, "I found them in a great state. A copy of the code, or cypher, in which confidential orders and other messages are sent to the fleet all over the world, and in which reports and messages are sent back, had disappeared during the morning. It was in charge of a Mr. Robert Telfer, a clerk of responsibility and undoubted integrity. He kept it in a small iron safe, which is let into the wall of his private room. It was safe when he arrived in the morning, and he immediately used it in order to code a telegram, and locked it in the safe again at 10.20. Two hours later, at 12.20, he went to the safe for it again, in order to de-code a message just received, and it was gone! And the lock of the safe is one that would take hours to pick, I should judge. There isn't a shade of a clue, so far as I can see, except this circumstance of Mayes being seen leaving by Corder--just between Telfer's two visits to the safe, you perceive. And of course there may be nothing in that, except for the character of the man. And that's all there is to go on, as far as I can see. I needn't tell you how important the thing is at a time like this, and how much would be paid for that secret code by a certain foreign Government. We have made hurried arrangements to have certain places watched, and as soon as I have taken you to the office I must rush off and make a few more arrangements still. But here we are." Mr. Robert Telfer's room was at the side of a long and gloomy corridor on the upper floor, and the door was distinguished merely by a number and the word "Private" painted thereon. We found Mr. Telfer sitting alone, and plainly in a state of great nervous tension. He was a man of forty or thereabout, thin, alert, and using a single eye-glass. Plummer introduced us by name, and rapidly explained our business.