In the spring of 1945, British and American military cameramen followed Allied troops into Bergen-Belsen and other newly liberated concentration camps and filmed what they found: mass graves, survivors barely able to stand, and German civilians marched through the camps by soldiers to confront the evidence. The footage became the basis for a documentary commissioned by the Psychological Warfare Division, produced by Sidney Bernstein with Alfred Hitchcock brought in to advise on structure and editing so the material could not later be dismissed as propaganda or fabrication. Trevor Howard narrates. Shifting postwar politics left the film unfinished and shelved, and it sat unseen for four decades until it was completed and broadcast in 1985. The film does not soften what the cameras recorded; bulldozers push bodies into pits and survivors describe conditions in flat, exhausted terms. Its value is partly historical evidence and partly a record of how the Allies tried, in real time, to build a document that a future world could not deny.