Smiling bleakly, Steve picked up a loose chunk of rock, tossed it at the anthrovac. The creature merely swung its huge body gracefully at the hips, avoiding the missile. Then it stooped, found a stone for itself, hurled it at Steve. He ducked, feeling completely and tremendously foolish. He should have been prepared, for the anthrovacs are playful and can mime almost any human action. He did not duck in time. He felt the stone _thunk_ against his helmet, peered with horror at the glassite inches from his face until he saw that it hadn't cracked. Grinning now, he shook his fist at the creature, watched it duplicate the motion with its great hairy hand. It was a game, Steve told himself, a lot like the meaningless conversation Teejay and Kevin had had to dispell the Ganymede-fear. _But if the anthrovac could mime human actions, perhaps the anthrovac could also mime voices!_ That would necessitate telepathic powers, naturally. But the anthrovac, like many denizens of terrestrial forests and tundras, changed its habits immensely in captivity. A captured anthrovac, one which had been reared with one of the circus troupes, could never tell you what a wild anthrovac was like. And a wild anthrovac, somehow living on airless Ganymede and taking its energy directly from cosmic and solar radiation, might be able to do anything. _I am Charlie Stedman...._ Steve carried the thought to its logical conclusion. Suppose an anthrovac--_this_ anthrovac which faced him now--had somehow heard Charlie speaking. Charlie might have been introducing himself to someone: "I am Charlie Stedman." But the hypothesis wasn't much more than a bubble, and it burst completely when Steve remembered he was the only one who could hear the voice. "Hey, Stedman! You trying to kill yourself?" Steve whirled, looked up. Two figures, no more than vaguely human in their cumbersome vac-suits, hovered over him, jetting around in circles. The anthrovac had seen them too--and now, apparently alarmed by the twin forms floating just out of reach, the creature turned and bounded away over the uneven terrain. "What gave you that idea?" Steve called into his intercom. "The anthrovac wasn't looking for trouble." "I don't mean that, stupid." Teejay had a way of jarring him back to reality with a few words. "I mean, how much air have you left?" Steve looked at the gauge. "Enough to return to the _Gordak_, provided I get on my horse." "We'll walk with you, then," said Teejay, and dropped to the ground at his side. "I think I'll hold onto your arm, too. You're liable to go wandering again, and we might not be able to find you." Kevin alighted, switched off his jets. "How about the voice, boy? Do you still hear it?" "Why--no! But I did a minute ago, until the anthrovac ran away." "That's peculiar." "There's a lot that's peculiar out here on Ganymede, Kevin. I think--" "Stop thinking and start walking," Teejay told him.