The Guardian of Isis

ISIS had been a pristine, remote planet when settlers escaping from an overcrowded, polluted Earth arrived. Now years have passed. The settlers have abandoned the technological knowledge of their fore-fathers. The history of the first inhabitants from Earth has been replaced by myth. But one young man yearns to know the truth, and soon he gets the chance to find it.

Monica Hughes's brilliant Isis trilogy is a classic of science fiction, creating a world that is enthralling, dangerous, and irresistible.