"I did what I could to keep my end of the thing going. But, you see, it was all so new to me. I hadn't got deep enough into the work to organize it the way I wanted to. There were a lot of little things that _couldn't_ be organized." "Why not?" "Well, this man Carlton, for instance, had Lockwood's office look after his English mail. All his letters had to be sent on to whatever point he reported from." "Well?" "When Lockwood was away from the office he deputized me to look after his mail, sign for the registered letters, re-direct telegrams, see that everything went through to the right point. It was quite a heavy mail. Carlton, I guess, was a man of importance, and besides that he was investing for friends at home. Looking after it, of course, was simple enough, but--" "Wait!" I interrupted. "Has this mail anything to do with our blank wall?" He looked about at me as though he had seen me for the first time, as though all that while he had been merely thinking aloud. "Why that is the blank wall," he cried. "How?" I demanded. "Four weeks ago Lockwood came back from the West. On the same day a registered letter came to the office for young Carlton. That letter held twelve Bank of England notes for a hundred pounds each. About six thousand dollars altogether." "Where did it come from?" "From Montreal, from Carlton's own father. He wanted the money forwarded to his son. The older man was on his way back to England. The younger Carlton was looking up certain lands his father wanted to invest in. Young Carlton's movements were rather uncertain, so his father made sure by sending the letter to our office--to Lockwood's office." "And you were still acting as _poste restante_ for the Carlton out in British Columbia?" "Yes, we'd been receiving and forwarding his mail." "And?" "We also received this registered letter from Montreal. That's where the blank wall comes in." "How?" "We've no record of that letter ever going out of our office." He looked at me as though he expected me to be more electrified than I found it possible to be. "Lost, stolen, or strayed?" I asked. "That's what I'd give my eye-teeth to know," he solemnly asserted. "But where do _you_ come in?" His answer was given without the slightest shade of emotion. "I signed for the letter." "Then you remember that much?" "No, I don't remember it. But when they began to investigate through the post-office, I knew my own signature when I saw it." "With no chance of mistake, or forgery?" "It was my own signature." "And you don't even remember getting the letter?" "I've gone back over that day with draghooks. I've thought over it all night at a stretch, but I can't get one clear idea of what I did." The force of the situation was at last coming home to me. "And they're holding you responsible for the disappearance of that letter?"