I went forward along the side deck. In the men's smoking lounge, amidships in the superstructure, I heard voices, caught a glimpse as I went past of Arthur Jerome, the television lecturer, and Livingston, the Earth Ambassador to Mars, in there with Green, the ship's purser. Did that mean that Brenda Carson and her brother were still on the forward peak? I went cautiously forward. They were there--the blobs of them, faintly starlit, showed where they were standing together at one of the side bull's-eyes. Upon impulse, instead of joining them, I slid unseen into the shadows of a loading engine. "Oh, Philip--" The girl's voice was faintly audible in the silence. "I'm so frightened. You think we can do it safely?" "Yes, of course. I'll make sure--" He lowered his voice and I lost the rest of it. "When?" she murmured. "I'll just take a look presently. We're not there yet--closer in a few hours." What, in Heaven's name, could that mean? Were these two spies, planted here on the _Seven Stars_ by the phantom-bandits? Were they discussing the attack which Captain Wilkes and I feared? Certainly it did not seem so. Young Philip Carson wasn't much older than his sister. Slim, handsome, rather effeminate-looking fellow, with a weak jaw and slack mouth. He wore black and white trousers, somewhat like hers. He and she seemed devoted to each other. Rankin had told me that Philip Carson had a bad record of gambling and bad companions. Was the girl entangled because of him? My mind went back to the meager details which Rankin had given me. Brenda and Philip Carson came of a cultured and once-rich family in New York. Their father--their only close living relative--had been a research physicist. An eccentric old fellow; he had built a laboratory down on Long Island where, working in secret, he was laboriously experimenting on something. Two years ago the place had exploded. Presumably he had been killed. But in the wreckage his body had not been found; nor was there anything to give a clue as to what he had been doing there. Had he been building the phantom space-raider? The thought was obvious now. Brenda and Philip had denied knowing, when the authorities had questioned them. And now they were going to Mars, on this of all voyages, and for no reason that they had been able to give. Was the vanished eccentric Professor Robert Carson the Phantom raider? My heart leaped as I heard another fragment from the girl. "You think you got his message correctly?" "Yes, of course I did." "If we can do it safely--Oh, Phil--the location." "I've got it all figured out, Bren," he insisted. "Even made a little map--got it in the wallet of my jacket." That stiffened me. I could see the blob of him standing there with her. The folds of his hooded cape, like hers, fell almost to his feet. But his arm held the cape draped a little to one side. I could see his white shirt; he was wearing no jacket. It would be in his sleeping cubby then.