"You've already found out more than anybody else even dared to guess!" she protested. "But not enough. We've stirred it up. It sent small fish in the lagoon here and elsewhere to report back to it. We can't guess what the fish reported, but we know some of it was about human beings. Whatever is down at the bottom of the sea must be interested in men. Remember? It made a patch of foam that swallowed up one ship and all its crew. It's interested in men, all right!" "True, but...." "We dropped the dredge, which implied that we were interested in it. The bathyscaphe indicated more interest on our part. To discourage that interest--or perhaps in self-defense--it wrecked the bathyscaphe." "It, Terry?" asked Deirdre. "Or _ellos_, they?" "They," he corrected himself coldly. "We killed the fish that were reporting men's doings from here. That was insolence on our part. So the hum at the lagoon entrance went off and, after two nights, started again--and then this huge squid was found in the lagoon. It should have been able to defend itself against us. It was sent up here because it was capable of defending itself! But we've killed it just the same. So now what will come up out of the depths? And what will it do?" Deirdre said firmly, "You'll be ready for it when it comes!" "Maybe," said Terry. "Your father once mentioned an instrument he'd like to have to take a relief map of the ocean bottom. Changed around a little, it might be something we need very badly indeed. The horn we've got is good, but not good enough. I'll talk to the electronics men here." There was a noise of scraping chairs, inside the dining hall. People came out, talking cheerfully. There was much to talk about on Thrawn Island today. The killing of a giant squid had been preceded by a specific guess that linked it to meteoric falls in the Luzon Deep. Logically, the excitement had grown. Terry found his electronics specialists, and explained to them the type of apparatus he was interested in. He asked if it was included in the island's technical stores. He wanted to assemble something capable of emitting underwater noises of special quality and unprecedented power. There is not much power involved in sound through the air. A cornet player manages with much effort to convert four-tenths of a watt of power into music. A public-address system for a large area may give out fifteen watts of noise. Terry described a device which could use a small amount of power, serving as a sonar or a depth-finding unit, and then, with the throw of a switch, turn kilowatts into vibrations underneath the sea. If powerful and shrill enough, such vibrations could be lethal. A technical argument ensued. Terry's demands were toned down to fit the equipment at hand. Then three men went with him to the island's workshop. They took off their coats and set to work.