'My assurance that it was absolutely certain that the lady in question was in entire ignorance of the whole affair, and was as much in the dark as we were as to the author of the letter, was received by him with incredulity. "I have been concerned in cases like this, or at least a good deal like it, a dozen--or, I might say, a score--of times. In every case the lady maintained stoutly that she knew nothing about it, that she had never written a letter to any man whatever, and had received none previous to the one that happened to fall into the wrong hands. In three or four instances I was deceived myself, but there is no telling with women. When a man tells a lie, he either hesitates or stumbles, or he says it off as if it were a lesson he had got by heart, or else he is sulky over it, and you have to get it out of him bit by bit, just as if, though he had made up his mind to lie, he did not wish to tell more lies than necessary. With a woman it is altogether different. When she makes up her mind to tell a lie, she does it thoroughly. Sometimes she is indignant, sometimes she is plaintive; but, anyhow, she is so natural that she would deceive Old Nick himself. Most of them are born actresses, sir, and when they take up a part they do it with the determination of carrying it through thoroughly." Of course, I told him that, whatever it might be generally, this case was altogether an exception; that it was a moral and absolute certainty that the lady had nothing to do with it, and that the investigation, when it was once undertaken, would have to proceed, say, on the line that the author of these communications was a man or a woman having a personal enmity against a lady, and instigated by a desire to annoy and pain her. '"Well, sir," he said, "of course, if you employ me in this matter it will be my business to carry it out according to instructions; but I am afraid that it is not likely anything will come of my search." '"But," I said, "there is nothing impossible or improbable in the fact that someone should have a grudge against her; she has just become engaged to be married." '"That alters the case altogether," he said quickly; "there may be some other woman who wants to marry the man, or there may be some one who may consider that she will be left in the lurch if this marriage comes off; and either of these might endeavour to make a scandal, or to get up a quarrel that might cause the engagement to be broken off. If you had mentioned about the engagement before, that is the first idea that would have occurred to me. There are very few things a jealous woman will stick at. The case looks more hopeful now, and when I come to know the man's name, I ought very soon to be able to put my finger on the writer of the letter, if it is a woman. At any rate, if there is no other clue, that is the one I should take up first."