Stalking Darkness

Description for STALKING DARKNESS by Lynn Flewelling:

A master of subterfuge, a rogue thief with a noble air, Seregil of Rhiminee has taught his young protege, Alec of Kerry, his greatest secrets of the trade. Together they've made their way with thieving jobs large and small, winning friends and enemies, their lives in constant danger and yet charmed by an aura of magic, friendship, and trust. But now, as their adopted country prepares for war, Seregil is called away by the ancient wizard Nysander to face the ultimate challenge of loyalties, and entrusted with a deadly knowledge that, if breached, could cost both Seregil and the unwitting Alec their lives. And as Alec learns the shocking truth of his own shadowed heritage, he, Seregil, and a handful of loyal companions are catapulted into a tumultuous conflict with the ultimate evil--in which magic alone may no longer shield them from harm....

This is #2 in Nightrunner Series.