"I've no idea," Terry told her. "I've got a feeling that the wise thing to do would be to settle down somewhere and buy a shop, and forget all this. If I don't think about it, maybe it'll go away." "I'll get my father and see what he says." "Tell him," commanded Terry, "that I want to try out my fish-driving horn. I'd like to have witnesses. If this foolishness has to be reported to somebody, we need evidence of the facts. I want to drive fish and see how many deep-sea ones there are in this lagoon, and how many of them have spy-devices on them." Deirdre turned away. Then she turned back. "Spy-dev--" "I slipped," said Terry. "I shouldn't have said that. Forget it. Just tell your father I have an extremely urgent impulse to drive fish, and would he come and help." Deirdre looked at him strangely, and went onto the wharf to search for her father. Terry paced back and forth on the _Esperance's_ deck. In a few minutes Davis and the crew-cuts appeared with Deirdre. But they were not alone. Straggling behind them came nearly all the personnel of the tracking station. There would be somebody on official duty, of course. But here was the bespectacled Dr. Morton; the bald young man who'd offered Terry beer; and the installation cook; a typist, and specialists in radar and other abstruse subjects. Deirdre said, "I told them about the fish-driving business and they want to see. They stopped arguing about last night's bolide to take ringside seats. All right?" Terry shrugged. He had the recorder already set up. He'd taken a section of the tape made where the sea was bright, at the place where the loudest of the unpleasant humming noise was recorded. He'd made a loop of it so it would play over and over. He played the much-amplified sound through the underwater horn held in the air. The result was a raucous bellowing noise. He lowered it into the water. The horn touched the surface and went under. Instantly, the fish of the lagoon seemed to go crazy. All the surface broke and writhed and splashed. There was an incredible number of fish. Terry turned the horn on one side. In this way, not all the water was filled with the intolerable noise, but only a net-like beam of it raced across the water. Within that line the fish continued to leap frenziedly. The rest of the lagoon suddenly quieted down. In a little while the beam's space, also, grew quiet. But that was because the fish that had been previously caught in it had escaped. "I'm afraid," said Terry, "that this isn't going to be very entertaining. I'm going to sweep the beam across the lagoon, pushing the fish ahead of it, until I should have them all in one small area." It was curious that he felt uncomfortable as he set about his task. But he'd experienced the sensation this sound produced. And it was not very pleasant.