Tregonsee and Camilla, then, set out to find "X"; not any definite actual or deduced entity, but the perpetrator of certain closely related and highly characteristic phenomena, viz., mass psychoses and mass hysterias. Nor did they extrapolate. They visited the last few planets which had been affected, in the order in which the attacks had occurred. They studied every phase of every situation. They worked slowly, but--they hoped and they believed--surely. Neither of them had any idea then that behind "X" lay Ploor, and beyond Ploor, Eddore. Having examined the planet latest to be stricken, they made no effort to pick out definitely the one next to be attacked. It might be any one of ten worlds, or possibly even twelve. Hence, neglecting entirely the mathematical and logical probabilities involved, they watched them all, each taking six. Each flitted from world to world, with senses alert to perceive the first sign of subversive activity. Tregonsee was a retired magnate, spending his declining years in seeing the galaxy; Camilla was a Tellurian business girl on vacation. Young, beautiful, innocent-looking girls who traveled alone were, then as ever, regarded as fair game by the Don Juan of any given human world. Scarcely had Camilla registered at the Hotel Grande when a well-groomed, self-satisfied man-about-town made an approach. "Hel-lo, Beautiful! Remember me, don't you--old Tom Thomas? What say we split a bottle of fayalin, to renew old--" He broke off, for the red-headed eyeful's reaction was in no sense orthodox. She was not coldly unaware of his presence. She was neither coy nor angry, neither fearful nor scornful. She was only and vastly _amused_. "You think, then, that I am human and desirable?" Her smile was devastating. "Did you ever hear of the Canthrips of Ollenole?" She had never heard of them either, before that instant, but this small implied mendacity did not bother her. "No, I can't say that I have." The man, while very evidently taken aback by this new line of resistance, persevered. "What kind of a brush-off do you think you're trying to give me?" "Brush-off? See me as I am, you beast, and thank whatever gods you recognize that I am not hungry, having eaten just last night." In his sight her green eyes darkened to a jetty black, the flecks of gold in them scintillated and began to emit sparks. Her hair turned into a mass of horribly clutching tentacles. Her teeth became fangs, her fingers talons, her strong, splendidly proportioned body a monstrosity out of Hell's grisliest depths. After a moment she allowed the frightful picture to fade back into her charming self, keeping the Romeo from fainting by the power of her will.