In the Enemy's Service (Annals of Alasia)

Enslaved when invaders take over Alasia, Anya discovers ways to spy on the enemy and slip information to the resistance. But then she uncovers a disturbing reference to her own family and is confronted by a stranger who seems to know her secrets. Holding her life in his hands, he claims to have proof that Anya’s father was involved in the betrayal that led to the Invasion itself.