Omega knew that his first important task was to get rid of the beast. The fear-haunted expression in Thalma's eyes brooked no delay. Accordingly they went to the ship, and each taking a small sack they filled them with depth bombs. Thus armed they floated out over the lake in quest of their enemy. But although quite shallow the water was opaque for the most part being discolored by vegetable matter stirred up by the monster, and the transparent portions were too deep for them to see bottom. Long and carefully they searched at a safe distance above the water, but no sight of the beast could be seen. Then hoping that a chance shot might reach and destroy him they passed to and fro over the lake's center and dropped their bombs. Great columns of water were sent high in air deluging them with spray. That was all. Still, they had no way of knowing whether a bomb had struck home. In spots the water was so violently agitated as to suggest that the monster writhed in a death struggle. But at last all became as quiet as before. * * * * * It now occurred to Omega to surround the lake with an invisible wall of electricity of such power as to electrocute the beast should he attempt to go over or through it. This was accomplished by increasing the power of his motors and by automatic controls projecting a high voltage potential through the air around the lake. And then in addition to other protective appliances already installed Omega put a similar wall about the cottage, much to Thalma's relief and delight. One night they had retired early, Thalma being weary and her time but a few weeks away. To the sweet strain of music which had been in the air for ages, they soon fell asleep. How long he had slept Omega could never guess, but he was awakened suddenly. He sat up bewildered and stared into the darkness, because for some reason all lamps were out. And then he became aware of a peculiar sound coming from afar. It was a queer noise combining the roar of the surf upon a rock-bound coast, the sigh of the night wind through a forest and the rumble of thunder. Suddenly it seemed to him that earth and cottage were trembling, and the walls of the room swayed and buckled as though smitten by a great wind. Frantically he rubbed his eyes, convinced that it was all a dream. But the noise drew nearer, thundered in his ears. In terror he got to his feet, tried to cry out. The words froze on his lips, for just then the wall before him crashed in as though struck by an avalanche. Then came a grinding, splitting jumble of sounds, the solid ground shook under the passage of some mighty force which increased for a moment followed by a piercing scream. Frozen with horror Omega stared around the wrecked room whose tottering walls seemed about to fall upon him. Where was Thalma? In a frenzy he stared into the darkness, felt over the couch. She was gone!