The story is set in the latter days of World War 2, against the backdrop of fierce combat on the eastern front. Brother's War is based on real events.

A wanderer named Jack DiMercurio secretly desires the life and wife of his more affluent friend, Andy Shelton. Past tensions resurface between the two men during an informal reunion at Andy's cottage on Lake Michigan. One heinous act allows Jack to draw close to Andy's wife Liz, but Jack finds living Andy's life is a dangerous lie.