Patricia A. McKillip 
Sorceress and the Cygnet [EPUB ebook] 

With hair the colour of the moon, Corleu was different from the other Wayfolk. He alone tried to free his wandering tribe from the unearthly swamp that ensnared them — and he alone dared to cross the forbidden threshold. There he found a strange dark house, a place of legends and gods, foreseen in the stars. And there, to save his people, began Corleu’s search for the heart of the Cygnet — and impossible treasure…But if legends are real, nothing is impossible.