Ketrik came in from Perlac, came fast, using the Frequency Tuner all the way. Now his great bulk came forward in the control-seat, his eyes fastened intently on the dark blue disk of Earth that loomed ahead. "Strange," he muttered. "Strange, no Patrollers! I expected an escort at least, if not a challenge!" But no one heard. Ketrik, as always, had come alone. The helio from Mark Travers, recorded on the sensitized receivers at Perlac, had been more than a summons and a plea; it had contained an