Nayan Ray is a historian who views life as a series of "exposures," a silent witness to the world's tragic past. But when the Củ Chi Tunnels pull him into the visceral reality of 1968, his detachment shatters. Forged in the earth's suffocating depths, a bond with young soldier Linh forces Nayan to trade observations for action. In this subterranean nightmare, the observer must finally fight-or be consumed by the history he was never meant to survive.