Antique Ladies and Gray Malevolence — M.G. Lewis

Third volume in the Nraak Confederation Series: Captain Mark Sterling had been allowed to return to Earth by the Nraak after helping them defeat and kill their overlords, the Nasuwarna. He had almost convinced himself that the Nasuwarna were truly gone when they invaded first his dreams and then his waking hours. The Nasuwarna demanded that he go to Seusae, the home world of the Seeshuse, now a subject race of the Nraak. He was to meet Suura, who had led his people in fighting the Nraak over five lifetimes. The Nasuwarna wouldn't explain why he had to go, but Mark's dread grew as he approached the planet, as he sensed that Suura was ensnared by his new allies, the Ekesyeda, and as he sensed what the Ekesyeda truly were. (Volume 1: An Orange Sherbet Sun in a Latte Sky ----- Volume 2: Blood Red Petals Ankle Deep)"