"Would he? We'll see about that. After a certain costumer with whom I am acquainted is through with you I don't think he would. But, supposing you were so effectually disguised that he could never recognize you, do you think you could fill the position and play your part?" "Yes, I'm sure I could. At all events I'm not afraid to try." "Good! That's the way to talk. I've been studying you closely, my boy, and feel sure that you could carry the thing through as well as any actor living." "Always providing that I can get the place. I have no references, you know." "That is easily fixed. The president of the Stock Exchange is a cousin of mine. You shall apply for that position this very morning with a letter from him. Do you understand the duties of such a position well enough to fill it?" "Oh, perfectly. I learned all that in the bank." "Then come with me at once," exclaimed Detective Hook, springing to his feet. "If you want to clear your name before the world--if you want to avenge the wrong done by that man Callister to you and yours--embrace this opportunity which fate has thrown in your path, and never rest until you have read his secrets through and through." CHAPTER XVIII. THE GHOST OF THREE OAKS APPEARS AGAIN. For an instant Elijah Callister stood riveted to the floor. Then, springing forward with a fierce imprecation upon his lips, he approached the door of the deserted chamber in the direction of which the ghostly figure of the dead Mrs. Marley had disappeared. It was firmly locked. He had himself thus locked it upon their first entrance, not from fear of intrusion--that was not to be expected in a mansion so utterly given over to rats and the dust of neglect as this--but from the natural tendency of a suspicious evil-doer to perform his acts behind barred doors. And even as he had left it so remained that great oaken door now. There had not been sufficient time for the woman, were she living, to have even turned the key, providing it had been in the lock. But the key was not in the lock--it snugly reposed at that very moment in the pocket of the man himself. Now, Elijah Callister did not believe in ghosts. Search the length and breadth of New York City over, and in all probability no less superstitious man than the stock broker himself could have been found. He shook the latch fiercely. It had not been disturbed--there could be no doubt of that. No other means of entrance to the chamber existed save by one of the windows, forty feet from the ground, at least. A strange sense of fear seemed to creep over him--a tightness about the heart. There lay his villainous companion stretched senseless upon the floor. Neither window could have been approached without passing directly by the place where the man lay, where he himself had stood. And yet the appearance had been a reality.