I nodded assent to the lady's speech. "Will you let me have the key of this piano?" I inquired. "The piano, sir!" she said falteringly. "That is my piano. What do you require the key of _that_ for?" And the colour came and went from her olive countenance, in a way that told me I had discovered the real thief in the merchant's wife. A train of thought passed through my mind as rapidly as messages are conveyed by the harnessed lightning over house-tops, beneath the solid earth, or under the sea. This was a curious little instance of kleptomania. The poor wife's morbid secretiveness, acquisitiveness, or whatever a phrenologist might call "the organ," was in large excess. I pitied her. Could I here abandon the search, and leave the poor lady's crime a mystery, or an undetected fact? No; that would not do. She, at least, had permitted the servant, my client, to be accused. I knew the depth of woman's cunning. I know how tenaciously one will cling to the outward forms of respectability and of virtue. I know how horribly unscrupulous a criminal at bay, with the chance of setting the dogs of the law on the wrong scent, could be. To relax in my vigilance would be fatal to my innocent client, whose late mistress, the real thief, would forge other proofs of the guilt of the guiltless. Why did I reason to myself thus? Does not innocence tremble, and lose its self-possession under the remotest suspicion of an offence? Does not guilt, as a rule, maintain its self-possession, and look with a bold front upon the perils of its situation? Yes. Ordinarily I see in embarrassment an indication, not of guilt, but of innocence. But in Mrs. Green's case there was a firmness with the embarrassment; there was an expression which I cannot describe in words. There was a dread of me visible in the attempt to hide that fear. There was an indescribable _something_, which operated on my mind as moral evidence. "I won't press for the key, madam, if you are unwilling to let me have it." "I am unwilling only, sir, because I think it an impudent request." "Madam," I replied, "no request can be impudent which is explained by the fact that I am collecting evidence to rescue innocence from ruin and shame." "I shall not give you the key of my piano." "Again, madam, I say I will not press you for it; but I will state, in the presence of your husband, that I think it necessary to know what is contained in that piece of furniture." Mr. Green was thunderstruck, and bewildered to the verge of insanity. A light dawned upon his mind, of which I was then unconscious. He recollected, as he shortly after told me, that not a week before, having entered the drawing-room, in order to meet his wife, on his return from the City about half an hour before his usual time, he found her sitting by the piano. She heavily closed the lid of it as he opened the door. It was a minute or two after this light dawned upon him before he recovered his self-possession enough to open his mouth.