There were the sounds of Walton bounding down towards the ship in the peculiar dancing glide demanded by the low gravity. Methodically, without looking up, Ballard continued his job, following Walton with his earphones. Only when the foundation fill was laid would it seem natural for him to stop working for a moment and go to the ship. Gradually, layer on layer, the plastic melted, coated the walls and hardened. He heard Walton reach the ship, then there was a slight ringing noise as the man touched his key-magnet to the airlock. As Walton entered the lock, his mike registered the pressure of air by suddenly picking up all the sounds of the ship; the throbbing of the generators, the intermittent rush and sigh of the air conditioner, and the close curved walls echoing back the scrape of his shoes on the locker room floor. Four minutes to go. Ballard finished melting the plastic onto the walls, resisting the urge to hurry and risk botching the work. Walton had no reason to kill him--except for the rotenite. And since its discovery, Walton had shown nothing but a surface friendship covering a hidden hatred and fear that was growing into surreptitious maneuverings towards murder. But with a pretense at normality, Ballard hoped Walton would get over his obsession and forget it, never knowing that he'd seen anything suspicious. And meanwhile Ballard had only to stay out of the way of accidents without seeming suspiciously careful. He added the last necessary layer of plastic, switched off the heat beam and stood up. There was no sign of motion around the _Minnow_. Walton had not come out, but Ballard's earphones continued to pick up Walton's nervous, irregular breathing. * * * * * Ballard started down the hill in long, low floating bounds. The _Minnow_ expanded up at him, a ship etched in black and white against a jagged mass of black and grey ores. Just before landing on his second bound, his earphones picked up a sharp metallic ringing note he couldn't identify. Suddenly the ship expanded up directly in front of him; he'd overshot his landing. He thudded into the ship, slid down to the ground and landed facing the lock, his key-magnet in hand. Again he heard the familiar tuning-fork note, this time ringing faintly up from the magnet in his own hand as he put it against the circle of lighter metal that was the lock. The circle turned, with the magnet rotating out into a handle. He grabbed it and yanked to slide back the airlock panel. The yank pulled him off his feet. For an instant he couldn't orientate; then he realized that _he_ had moved because the panel had not. It was a case of action or reaction. The panel had not budged, seeming to be one with the flawless sweep of the hull. He tried again, yanking it with the same futile results. Apprehension flooded through him. "Walton!" he called. "Walton, the panel's stuck! Open it from the inside!"