Whatever the _Esperance's_ purpose was, there was nothing mystical about it--not if a flattop parted with rare and expensive specialized vacuum tubes to try to help, and the police department of Manila urged Terry tactfully--through Horta--to join the yacht, and no less than a Navy Captain had named him as someone to be recruited. Deirdre came abovedecks and replaced Tony at the wheel. The _Esperance_ sailed on. A last-quarter moon was now shining low on the eastern horizon. It seemed larger and nearer to the earth than when seen from more temperate climes. The wake of the yacht glowed in the moonlight. The wide expanse of canvas made stark contrast between its moonlit top and its shadow on the deck. The only illumination on the ship was the binnacle lights and the red and green running lights. Deirdre kept the _Esperance_ on course. Terry went up to where she sat, beside the wheel. "I've been making guesses," he told her. "Your father.... I believe that his curiosity has been aroused by something, and he's resolved to track it down. I strongly suspect that at some time or another he's gotten bored with making money and decided to have some fun." Deirdre nodded. "Very good! Almost completely true. But what he's interested in is a good deal more important than fun." Terry nodded in his turn. "I suspected that too. And it's rather likely that you've got a volunteer crew instead of a professional one because these young men consider it a fascinating adventure into the absurd, and because they'll keep their mouths shut if something turns out to be classified information." "My father's doing this strictly on his own!" said Deirdre quickly. "There's nothing official about it. There isn't any classified information about it. This is a private affair from the beginning!" "But in the end it may turn out to be something else," said Terry. "Y-yes. We don't know, though. It's impossible to know! It's--ridiculous!" "And my explanation for your being so mysterious with me is that you and your father insist that I find out everything for myself because I'd think it foolish if you told me." Deirdre did not answer for a moment. There was a movement behind Terry, and Davis came on deck. "That was good music!" he said pleasedly. "You missed some very interesting sounds, Deirdre! You too, Holt." "He's decided," said Deirdre, "that we're a little bit ashamed of our enterprise and won't tell him about it for fear he'll simply laugh at us." Terry protested, "Not at all! Nothing like that!" "When some forty-odd people have been killed by something inexplicable at one time that we know of," said Davis, "--and we don't know how many others have been killed at other times, or may be killed by it in the future--I don't think that's a laughing matter."