They questioned us. They were satisfied at last that, though the secret had escaped, we had not given it away. Hearing it discussed, it occurred to me to wonder why Carter was concerned. I was not aware that he knew of Grantline's venture. I learned now the reason why the _Planetara_, upon each of her last voyages, had managed to pass fairly close to the Moon. It had been arranged with Grantline that if he wanted help or had any important message, he was to flash it locally to our passing ship. And this Snap knew, and had never mentioned it, even to me. Halsey was saying, "Well, apparently we can't blame you: but the secret is out." Snap and I regarded each other. What could anyone do? What would anyone dare do? Captain Carter said abruptly, "Look here, lads, this is my chance now to talk plainly to you. Outside, anywhere outside these walls, an eavesdropping ray may be upon us. You know that? One may never even dare to whisper since that accursed ray was developed." Snap opened his mouth to speak but decided against it. My heart was pounding. Captain Carter went on: "I know I can trust you two more than anyone under me on the _Planetara_." "What do you mean by that?" I demanded. "What--" He interrupted me. "Just what I said." Halsey smiled grimly. "What he means, Haljan, is that things are not always what they seem these days. One cannot always tell a friend from an enemy. The _Planetara_ is a public vessel. You have--how many is it, Carter?--thirty or forty passengers this trip tonight?" "Thirty-eight," said Carter. "There are thirty-eight people listed for the flight to Ferrok-Shahn tonight," Halsey said slowly. "And some may not be what they seem." He raised his thin dark hand. "We have information...." He paused. "I confess, we know almost nothing--hardly more than enough to alarm us." Captain Carter interjected, "I want you and Dean to be on your guard. Once on the _Planetara_ it is difficult for us to talk openly, but be watchful. I will arrange for us to be doubly armed." Vague, perturbing words! Halsey said, "They tell me George Prince is listed for the voyage. I am suggesting, Haljan, that you keep your eye especially on him. Your duties on the _Planetara_ leave you comparatively free, don't they?" "Yes," I agreed. With the first and second officers on duty, and the Captain aboard, my routine was more or less that of an understudy. I said, "George Prince? Who is he?" "A mechanical engineer," said Halsey. "An underofficial of the Earth Federated Catalyst Corporation. But he associates with bad companions--particularly Martians." I had never heard of this George Prince, though I was familiar with the Federated Catalyst Corporation, of course. A semigovernment trust, which controlled virtually the entire Earth supply of radiactum, the catalyst mineral which was revolutionizing industry. "He was in the Automotive Department," Carter put in. "You've heard of the Federated Radiactum Motor?"