Oath of Fealty (Paladin's Legacy)

For the first time in nearly twenty years, Elizabeth Moon returns to the thrilling realm of her superb Deed of Paksenarrion trilogy.
 
Thanks to Paks’s courage, the long-vanished heir to the half-elven kingdom of Lyonya has been revealed as Kieri Phelan, a formidable mercenary who earned a title—and enemies—in the neighboring kingdom of Tsaia, where Prince Mikeli suddenly faces the threat of a coup. Acting swiftly, Mikeli strikes at the powerful family behind the attack: the Verrakaien, magelords steeped in death and evil. Mikeli’s survival—and that of Tsaia—depend on the only Verrakai whose magery is not tainted with innocent blood. Two kings stand at a pivotal point in the history of their worlds. For dark forces are gathering against them, knit in a secret conspiracy more sinister and far more ancient than they can imagine.