"What I mean is, the advance guard of an invasion force. The alien finds the satellite and, being telepathic, parks here a while to see what's going on." He giggled self-consciously. "I'm speaking imaginatively, of course. The alien moors here and reads our minds; finds out we have a load of bombs here that can blow up the works down there. So he comes drifting out of the ship and takes over someone of us here. When no one else is looking--_poof!_--Earth is destroyed like that!" Again Beveridge giggled. Gregson looked at him sourly. "You better leave those crazy magazines alone, Beveridge." But Lasseux interjected, "We should devote careful attention to what he has said. There may be a grain of truth in it. After all, _who moored the spaceship_?" A moment's silence. Then the Russian said, "Assuming one of us is an alien--not that I believe Beveridge's fanciful story--how would we know? Until Earth is destroyed, that is?" "That's just it," said Lal gloomily. "We _wouldn't_ know. Not until it was too late." * * * * * What began as Beveridge's dinner-table joke soon became an earnestly-held belief. Perhaps it was the strain of life aboard the satellite, 10,000 miles above the Earth's surface. Perhaps the tensions of a year's isolation from the rest of humanity were taking their toll. But, from a dinner-table jest, the concept soon became a source of serious discussion. And tension. Tension wrapped cold fingers around them as the days passed. They agreed to operate in teams, never to let one out of another's sight, always to keep constant watch ... for there was no way of telling which of them harbored in his body or his mind Earth's potential destroyer. Two days passed this way, and a third. Then Lal went for a walk in space--without a suit. "He cracked," Gregson said, staring at the Indian's corpse. "This crazy alien business--it just broke him apart." "Yes," Lasseux said moodily. "The tension ... the looking and spying ... he couldn't take it any more. Our first casualty. But not the last, I fear." Beveridge and Gregson brought Lal's body in--it was orbiting around the Wheel--and a brief funeral service was conducted. The Indian's body was fed to the atomic converters that ran the station and consumed in an instant's blaze of light. Lasseux radioed Earth and gave them a full account of the tragedy. He was told that a replacement for Lal would be on his way within a week or two. "Now there are just four of us," he said, turning from the radio. "It will make keeping watch easier. I will team with Golovunoff for the rest of the day; you two English-speakers can work together." They did. It was a cold, cheerless day. The little Indian had everyone's spirits. Then Beveridge suggested, "Perhaps Lal was the one carrying the alien. When he discovered the truth he ran out into space, killing himself and the alien...?"