While Dyke Darrel stood debating what course to pursue, under the remarkable change in circumstances, the mad girl uttered a sudden, sharp cry. "See! it is Hubert, my Hubert! come at last!" A look of mad joy sped across the white face, as one slender arm was extended, pointing toward the window. Dyke Barrel followed with his eyes, and then he, too, uttered an involuntary cry. Glued to the narrow pane was a face that was startling in the intensity of its ghastly pallor, but it was not this that sent an involuntary exclamation to the lips of the railroad detective. The face at the window was that of his friend, HARPER ELLISTON! His presence here was one of the mysteries of that eventful night. CHAPTER XII. A BURNING TRAP. For some moments Dyke Darrel stared at the face in the window without moving. How came Harper Elliston in the woods at Black Hollow, when he ought to have been in Chicago, according to his expressed intentions of the previous day? With a sudden, wild scream the crazed Sibyl darted across the floor, and thrust her hands against the window with such violence as to burst the glass, cutting her hands severely in the operation. "Hubert! Hubert! come at last!" The girl staggered back and sank in a paroxysm to the floor. It was indeed a startling affair, yet Dyke Darrel did not lose his presence of mind. He hurried to the door and opened it, springing outside quickly. "Elliston, I want you." Dyke Darrel stood by the broken window now, but the man he had expected to find was not there. The apparition had vanished as though fleeing into the upper air. Again the detective called the name of his friend, but without receiving a reply. Here was a mystery indeed. Had that face at the window been an optical delusion, after all? Dyke Darrel was not superstitious, yet in the present case a queer feeling oppressed him, and an awful misgiving entered his mind. "I cannot believe that the face at the window was other than that of Elliston's; and yet she called him Hubert. It must be that there is a mistake somewhere, and it seems to me that the mad girl is more apt to be deceived than I." Once more Dyke Darrel returned to the house. Sibyl Osborne lay in a dead faint on the floor. The detective began chafing her hands at once, and loosened her corsage. A morocco case fell to the floor. It was the one containing the alleged picture of Hubert Vander. Under the circumstances Dyke Darrel believed he was justified in examining it. He opened the case, and was soon gazing at the face of a handsome man. Although smoothly shaved, the face of the photograph was that of Harper Elliston! A horrid suspicion now took possession of the detective's brain. Securing case and photograph on his own person, Dyke Darrel proceeded in his efforts to bring the girl back to life. He was soon rewarded. "It was Hubert."