"Stay close to me! I'm one of the veterans." "Bring Vulc, we're about ready," the Commander's voice sounded startlingly inside Mark's headpiece. "Who's Vulc?" Mark asked Carston in a whisper. Before the latter could answer, there was a sudden unearthly rumbling behind them. Mark turned, stared, then froze in his tracks. A huge, awesome apparition was lumbering in a straight line for the Commander. It was vaguely human in that it possessed a head, torso, four limbs of elephantine proportions, and it waddled upright. But the human resemblance went no further. The creature's skin, if skin it was, gleamed silvery metallic and gave the impression of being fluid! It reminded Mark of nothing so much as an immense blob of mercury that might at any moment collapse into a puddle and spread over the floor. But Vulc didn't collapse. He approached the Commander and stood docilely waiting. She patted the creature's arm and then handed him a package of something. Vulc rumbled his appreciation and poured the contents into a gash that appeared in his face. Then he waddled contentedly to a large sled and took up the reins. "Wow! Where did you ever dig up _that_?" Mark turned white-faced to Carston. "Vulc? He's a native of this planet, but more than that, he's our ambassador of peace!" The Commander's crisp voice made further conversation impossible. "Single file, you men. Stay as close to each other as the sleds will permit. Carston, you stay in the middle, as usual, and watch out for the Blitzees. If you men work hard, we should be back within ten hours." Silently the outer door of the lock slid open and the men began to file out, with the gigantic Vulc at the head. The brightness was intense, although they were on the planet's "dark side." Shimmering waves of heat danced before them over the flat terrain. At the very end of the line Commander Cynthia kept pace with them. * * * * * "What did you mean by 'ambassador of peace,' Carston?" Mark had purposefully fallen into line next to him. "Adjust your radio-phone to its shortest distance communication," Carston directed him, "so it will be inaudible to anyone else." As Mark did so, Carston continued, "We couldn't get out the metal we're after, without Vulc. His home is on the Neutral strip where we're going--that part of the planet where the outward and sunward side meet. All of Vulc's kin are there, and they resent us. They have attacked us before. We bring Vulc as an evidence of friendly intentions; they have a speech of sorts, and Vulc's supposed to pacify them." "What was it the Commander gave him before we left?" "Powdered metal, filings, and tiny scraps from the factories. That's what's in those big sacks up there on Vulc's sled--a peace offering for his people." "They subsist on metal!" Mark Denning was aghast.