Ice Crown, a novel by Andre Norton. Forerunner artifacts were the most valuable things in the known universe. Every one found was a possible clue to the grandeur and power of a people who had disappeared before the very Earth itself existed. There was reason to believe that a Forerunner power rested in the famous Ice Crown of the closed planet Clio. The result of Psychocrat mind-blocking, Clio was a mass of conflicting nations - of barbarism and hidden wonders, and absolutely banned to the probers of the civilized galaxy. Nevertheless Offlas Keil and his niece Roane broke the quarantine, and made their secret landing... and thereby primed a social atomic bomb that all the laws of the Service had been set up to prevent - with Roane as the potential detonator.