Traitor
(Book)

In 1944, the Polish city of Lwów has been liberated from Germany but is caught among the insurgent armies of several countries and its resistance fighter; in this city, loyalty comes second to self-preservation. In order to eat, Tolya joins the Red Army but is rescued by Ukranian freedom fighters after he murders a Soviet officer in the street. That doesn't mean he trusts them, though.

Poland, 1944. After the Soviet liberation of Lwów from Germany, the city remains a battleground between resistance fighters and insurgent armies. Tolya Korolenko is half Ukrainian, half Polish, and he joined the Soviet Red Army to keep himself alive and fed. When he not-quite-accidentally shoots his unit's political officer in the street, he's rescued by a squad of Ukrainian freedom fighters. They might have saved him, but Tolya doesn't trust them. In a city where loyalty comes second to self-preservation, a traitor can be an enemy or a savior-- or sometimes both. -- adapted from jacket