Dave frowned thoughtfully. The expression, "out of phase" came to mind, and he decided that the half-world was displaced, out of phase in time, moving behind one peak of the "real world" and before the next. He remembered seeing a series of synchronizing pulses depicted on an oscilloscope; a series of rectangular waves, square-sided and flat-topped, rising from the baseline sharply. Like the cross-section of a row of piano keys, the separation between pulses very narrow compared to the width of the flat top. This half-world, he supposed, moved along in the separation. "Where is Claverly--and Phelps?" "I don't know. Another crew captured them and took them back." "I think that's about enough," said Dave. "I think we can take it from here." "And what are you going to do with me?" Dave grinned, "We'll make a sporting proposition out of this, superman. You'll be the bait for a trap. If the trap springs on me, you'll win. If the trap springs on you, well, that's just too damned bad!" "You can't trap us!" "No? You told me I couldn't get anything out of you, either. So just watch!" Dave lifted the 'copter once more and drove, at headlong pace, back to Merion. He hovered thirty feet above the pseudo-ground, less than half a mile from the main building, and then cut the engine and let the helicopter drop. For good measure, he tilted it sidewise. The ship landed with a jarring crash that crumpled the landing gear and folded one of the rotor blades down. The hull crumpled in on one side, and a litter of broken glass and some splinters of metal spread out across the earth. Dave completed the picture by kicking out the fore window and strewing the ground around the ship with the gear from the various tool boxes and compartments. He found a first-aid kit. He charged a hypo needle with a healthy slug of sedative and placed it handy. Then he sat back and waited. An hour passed; two, three, and darkness began to fall. Dave switched on the landing lights of the 'copter, and then with a vicious smile he kicked one of them loose so that its beam cut the ground askew, illuminating the litter on the ground. Two hours after dark he was rewarded by the distant sound of another helicopter. Dave went to work vigorously. He clipped the pilot across the jaw, dazing him. He shoved the needle home and discharged the sedative into the pilot's body. Then he cut the tape and shoved the feebly-struggling body half out through the fore window, being callously rough so that the pilot's face and shoulders were slightly cut by the broken glass. The pilot, roused a bit by the pain, waved at the oncoming helicopter, trying to warn it off. Instead, the other pilot dropped rapidly towards the wreck. It landed a hundred feet away and two men dropped to the ground and came running. "What happened?" cried the foremost. "Wreck," groaned Crandall, inside the ship. He took careful aim with the pilot's rifle and fired, twice. Both men dropped in their tracks.