"Yes. He told us what happened to the Boston man who came here. It was plain to me that he wanted us to keep away. He ran down ahead of us, and he is on the island. Why should he care to frighten us away? Why should he hurry to get here ahead of us? I tell you, old man, this is a mystery worth solving." Bruce grunted. He felt that Merriwell was right, but he realized it might not be an easy thing to solve the mystery of the island. The big Yale man stood looking out of the window and watching the boat, while Frank continued his investigations. Merriwell wandered from room to room, and at last descended the stairs again. "If he gets an idea that there is really a wonderful mystery here," muttered Bruce, "he will stay till he has solved it if he spends the remainder of the summer in this vicinity. Never saw a fellow who took such an interest in anything mysterious." The wind was rising again. It rattled a window, and somewhere about the building it made a loose board clap, clap, clap, in a way that made Browning think of clods falling on a coffin. All at once, somewhere down below in the old building, a shriek rang out, startling, shrill, wild and awful. It froze the blood in Browning's veins and seemed to cause his hair to stand upon his head. Following the shriek came--silence! CHAPTER XX. FRANK SEES THE MONSTER. Instantly Browning thought how the fisherman had told of the awful screams that came from the lips of the monster of the island. Had that monster uttered this cry? Where was Merriwell? "Frank!" Browning shouted the name of his friend and the empty rooms echoed with the sound. "Frank Merriwell!" From room to room rushed the big fellow. There was no answer to his cries. Quickly satisfying himself that Merriwell was nowhere in the upper story of the boarding house, Bruce bounded down the stairs four at a time. "Frank, where are you?" No sound save his own voice and the echoes. A sickening sensation seized upon Browning. He began to feel that a calamity, a tragedy, had taken place. From room to room he rushed, but he saw nothing of the one he sought. Was it possible Frank had left the building without saying anything to him? He could not think so. All at once he stood before an open door, and he dimly saw a flight of stairs leading downward into the darkness. A cold, dank smell came up from the depths below. Browning quickly decided that there must be some sort of a cellar or basement down there. The door was open. Frank had gone down to investigate. But the cry that had rung through the building! What had happened below? For a moment Bruce hesitated. Then he quickly felt in his pocket and drew forth a match safe. A moment later, with lighted match in his fingers, he was descending the stairs into the dank and moldy basement. At the bottom of the stairs was another door. It was open. Bruce stepped through it and stumbled over something, dropping his match, so that he was in the densest darkness.