"A fine delineation of an alien civilization" and "a well-realized heroine" propel this sci-fi adventure thriller from the author of the Dragon Quartet (Andre Norton, author of Catseye).   After six years in a maximum-security prison, political dissident and photographer Jude Rowe will take freedom at whatever price it is offered. She's naturally suspicious of the authorities' deal--liberation from the Wards in exchange for her service on the paradise planet of Arkoi. A parallel world to the overpopulated and environmentally depleted Terra, Arkoi has enough open land and raw materials to revitalize a dying Terra, making it a playground for scientists and a resort for the ultra-rich.   The Terran colony spreads like a blight, pushing at its boundaries, subjugating Arkoi's improbably small and seemingly primitive native population, and threatening to destroy a world that has existed unchanged for centuries. Yet, every Terran expedition past the colony's borders has ended in death or insanity, spurring rumors of Others and Dark Powers lurking beyond the ring of mountains called the Guardians.   Now, accompanied only by an enigmatic Arkoi guide, Jude is forced to set out on her own daring expedition. What she discovers about Arkoi, the colony, and herself, will radically alter her mission and the dangerously entwined fates of Terra and Arkoi. What lies outside the mountains has claimed the lives and minds of many, while consumption and conservation clash in the valley below. Do the Guardians protect . . . or imprison?