Beaty, Erin. Traitor's trilogy #3

Sequel to: The traitor's ruin

After an assassination attempt, Sage and her fiancé attempt to undercover who the traitor is and work to avoid a war with another country

Once a spy and counselor to the throne, Sage Fowler secured victory for her kingdom at a terrible cost. Now an ambassador representing Demora, Sage faces her greatest challenge: avoiding a war with a rival kingdom. After an assassination attempt destroys the chance for peace, Sage and her fiancé Major Alex Quinn seek to reveal the culprit. But the stakes are higher than ever, and in the game of traitors, betrayal is the only certainty. -- adapted from jacket