Milan, a reclusive archivist, spends nights reviewing the decaying reels. The film, “Shadows of the Danube,” was meant to be a documentary about a forgotten village, Travnik , destroyed in 1999 under mysterious circumstances. The edited version released publicly showed only the tragic aftermath. But the uncut footage, Milan realizes, holds raw, damning scenes: local officials colluding with rebel forces, civilians being taken prisoner, and a secret execution site.