Dying of the Light (1977)

A whisperjewel summoned him to Worlorn, and a love he thought he'd lost. But Worlorn isn't the world Dirk t'Larien imagined, and Gwen Delvano is no longer the woman he once knew. She is bound to another man, and to a dying planet that is trapped in twilight, forever falling toward night. Amid this bleak landscape is a violent clash of cultures in which there is no code of honor--and the hunter and the hunted are often interchangeable. Caught up in a dangerous triangle, Gwen is in need of Dirk's protection, and he will do anything to keep her safe, even if it means challenging the barbaric man who has claimed her--and his cunning cohort. But an impenetrable veil of secrecy surrounds them all, and it's becoming impossible for Dirk to distinguish between his allies and his enemies. While each will fight to stay alive, one is waiting for escape, one for revenge, and another for a brutal, untimely demise.From the Trade Paperback edition.