"'When you employ a detective officer, sir,' he began, 'don't employ a man you can't put entire confidence in. If you can't trust him don't have anything to do with him; for if he isn't to be trusted with the dearest family secret that ever was kept sacred by an honest man, why he's a scoundrel, and you're much better off without his help. But when you've got a man that has been recommended to you by those who know him, trust him, and don't be afraid to trust him, don't confide in him by halves; don't tell him one part of your story, and keep the other half hidden from him; because, you see, working in the twilight isn't much more profitable than working in the dark. Now, why do I say this to you, Mr. Austin? You know as well as I do. I say it because I know you haven't trusted me.' "'I have told you all that was absolutely necessary for you to know,' I said. "'Not a bit of it, sir. It's absolutely necessary for me to know everything: that is, if you want me to succeed in the business I'm engaged upon. You're afraid to give me your confidence out and out, without reserve. Lor' bless your innocence, sir; in my profession a man learns the use of his eyes; and when once he's learnt how to use them, it ain't easy for him to keep them shut. I know as well as you do that you're hiding something from me: you're keeping something back, though you've half a mind to trust me. You took out a letter three times while we wore sitting opposite to each other in the railway carriage; and you read the letter; and every now and then, while you were reading it, you looked up at me with a hesitating you-would-and-you-wouldn't sort of look. You thought I was looking out of the window all the time; and so I was, being uncommonly interested in the corn-fields we were passing just then, so flat and stumpy and picturesque they looked; but, lor', Mr. Austin, if I couldn't look out of the window and watch you at the same time, I shouldn't be worth my salt to you or any one else. I saw plain enough that you had half a mind to show me that letter; and it wasn't very difficult to guess that the letter had some bearing upon the business that has brought us to Winchester.' "Mr. Carter paused, and settled himself comfortably against the corner of the chimney-piece. I was not surprised that he should have read my thoughts in the railway carriage. I pondered the matter seriously. He was right in the main, no doubt; but how could I tell a detective officer my dearest secret—the sad story of my only love? "'Trust me, Mr. Austin,' my companion said; 'if you want me to be of use to you, trust me thoroughly. The very thing you are hiding from me may be the clue I most want to get hold of.' "'I don't think that,' I said. 'However, I have every reason to believe you to be an honest, conscientious fellow, and I will trust you. I dare say you wonder why I am so much interested in this business?'