Oath of fealty - Elizabeth Moon

A death has made Kieri Phelan king of Lyona. Here humans and elves live in uneasy peace, united only by their failure to see the dangers at their borders. Harmony has never been more important - or elusive. But will Kieri's soldier background allow him to navigate these difficult politics? And can he awaken the powers his mixed blood confers?

An older evil also threatens, affecting not just Lyona but all surrounding kingships. The Verrakai family has been practicing forbidden blood magic for generations, and its scions are becoming bold. When they infiltrate a foreign court and assassinate key nobles, it's clear they must be controlled or eradicated. Phelan will send Dorrin, the only Verrakai he can truly trust, on this mission. She must overcome her abhorrence of the power that is her birthright and awaken her own hidden magic. This will lead to secrets and a mystery that neither Phelan nor Dorrin could have anticipated.