Had he not been barely minutes through the Barrier with the comptometers still warm, the insistent radar signal wouldn't have been worth its interruption of his thoughts. But anything so close to the Barrier demanded at least cursory investigation. He flicked a radar panel relay to TRACK. The object's speed was building up. It was without a doubt a controlled acceleration. No school kid could fail to recognize a comptometer-regulated trajectory. Within seconds his fingers were flicking across a three dimensional plot-check. _Headed for a Barrier-bust!_ Cragin checked the comps back in, mentally replotting a new trajectory of his own for them to pick up as he did so. As his hurtling craft entered a sliding, almost too-closely cut parabolic reversement, he cut in his com-beam. "This is Cragin, Stellar Patrol, please ack, whoever you are. You are heading for the Barrier. You must alter course. You have not more than three minutes. Acknowledge please if you read me." He waited, wondering. There was no answer, just the emptiness of the void echoing hollowly to the eternal half-whisper of Infinity. But--the track altered! The ship was slowing, curving off! Forty seconds went by, and it had gone into an oblique drift. For the first time in nine years there was a sweaty feeling in the palms of his hands, in the stubble of his upper lip. He cut his comps out, hauled his ship into a paralleling trajectory, then angled a gradual interception path. "This is Cragin," he repeated. His voice felt husky as though he had not used it for a century. "I am friendly. I intend no trouble. It is for your safety that I request permission to board you. Have information essential to your flight...." There was no ack. He had his space-helmet dogged tight as he slid alongside the slender, dark-hued craft whose jets had been choked to the lazy, red-hued combustion of idling speed, and reached for his Krells. He hesitated, let them remain hanging on the bulkhead. He had said he was coming as a friend. He flicked a single A-intensity magnetic tractor to the craft that seemed to float motionlessly beside his own, scrambled along it on his spacesuit's mag-unit, and was still perhaps five feet from the smooth side of the silent ship when an airlock growled open to receive him. Once shut behind him, he tried to trace a million half-finished thoughts as the lock chamber cycled up to pressure. Who was in here? Scientists who had long since learned the secret of the Barrier? Hardly, or his warning would have gone unheeded save for a polite acknowledgement. Who then--another explorer as Fowler Griffin had been? Or someone else who had stumbled onto the presence of the X Ecliptic and the machine-planet? Or some alien flightmaster of some foreign universe who was either exploring or lost, as he had been lost.... A blue light flashed the intergalactic symbol for PRESSURE and the inner lock slid back. * * * * *