The tide was going out, and already the black ledges were rising out of the water in the distance. Those were called "half-tide ledges" by the fishermen. There were other black rocks which rose barren and bleak above the highest tides. Near those ledges at certain seasons of the year sportsmen set their "tollers," or decoys, and crouching in nooks of the rocks, fired hundreds of shots at the sea birds lured to their doom by the wooden representations of their mates. Merriwell found a place where he could sit in a sheltered spot and watch the sailboat, at the same time having a good view of the bay and the islands and ledges. As he sat there Frank meditated on the mystery of the island. He was fully convinced that there was some reason why certain human beings desired to frighten all others away from the place. That the man from Boston had been murdered and buried on that island was quite probable. Perhaps he had been murdered for booty; perhaps he had discovered the secret of the island, and his death had been accomplished in order to seal his lips. In the latter case there must be some powerful reason why the desperadoes who slew him did not wish the secret revealed to the world. These thoughts led Merry to the conclusion that some criminal business was carried on upon that island. He was well aware that he was taking desperate chances in trying to find out what sort of business it was, but the mystery lured him on, and the very fact that there was danger lent a fascination to the adventure. How long he sat there thinking thus he did not know, but at last he was startled by a sound near at hand. He turned quickly and what he saw brought him to his feet with a bound. Peering from the bushes was the most horrible face he had ever looked upon. It was twisted and contorted in a frightful manner, the lips were drawn back from long, yellow fangs, the eyes seemed to glare like coals of fire, and about these frightful features tumbled a mass of tangled hair. "The monster!" That thought flashed into Frank's mind. He had no doubt but he was face to face with the creature that had frightened the simple fishermen from the island. For some moments Frank stood there, staring at that horrible face. Then a clawlike hand came out through the bushes and seemed to reach toward him, while a howl that was blood-curdling came from the creature's lips. That sound was the same that had frightened the fishermen into running for their lives, but, instead of running, Frank made a dash for the creature, Browning's revolver grasped in his hand. It was a most astonishing move on the part of the boy. For a moment the monster of the island remained motionless, and then that horrible face disappeared. With a leap, Frank plunged straight into the bushes, ready to grapple with the thing. He found nothing! It had vanished! Swaying bushes close at hand guided him, and he scarcely paused an instant. Straight forward he rushed, ready for the encounter at any instant.