Of the myriad methods director Robert H. Lieberman uses here to paint a picture of Cambodia’s complex history, the most striking is traditional shadow puppetry.

The vivid scenes, with their intricate silhouettes, offer an artful remove from the horrors being described. It’s a brief respite: the documentary bears witness to multiple firsthand accounts—from child soldiers, orphans, politicians, diplomats, aid workers—of the Khmer Rouge chaos. (At one point, citizens recall the genocidal regime even targeting people who wore glasses.) The result is compelling—one of the clearest, most complete historical maps of how such a peaceful country could descend into a bloodbath. And a sober warning that it could happen anywhere.