A Rumor of Angels — Marjorie Bradley Kellogg

the maximum security prisons where Earth permananentlky disposes of its most troublesome citizens. Jude Rowe has survived six years in the Wards, and now Earth Intelligence is offering her a way out. The price - a one way trip to Arkoi, an Eden-like planet, with its childlike, primitive natives and its thriving human colony. But there is something terribly wrong with this picture of paradise.

Every expedition sent beyond the colony's borders has disappeared. The few survivors who eventually struggle back are totally, permanently insane. Are Arkhoi's natives not as docile as they seem. Or are there some Others out there ready to destroy any humans who stumble int their territory? Can Jude alone succed where whole expeditins have failed? Or will she too vanish without a trace while the two worlds whirl closer and closer to final cataclysmic confrontation?