Exile's Gate

Science Fiction by Carolyn J. (Carolyn Janice) Cherryh

Blurb

Exile's Gate is a 1988 science fantasy novel written by C. J. Cherryh. It is the fourth of four books comprising The Morgaine Stories, chronicling the deeds of Morgaine, a woman consumed by a mission of the utmost importance, and her chance-met companion, Nhi Vanye i Chya.
It is tenuously set in her Union-Alliance universe, but has little in common with other works in that milieu.