Klaus Barbie ran the Gestapo in occupied Lyon, torturing resistance fighters and sending thousands of Jews, including children from the Izieu orphanage, to their deaths. After the war he vanished into Bolivia under a new identity, protected for years by intelligence networks that valued his anti-communist usefulness more than his crimes. This film follows Beate Klarsfeld and her husband Serge, a German activist and a French Jewish lawyer whose father died at Auschwitz, as they spend decades tracking Barbie down, confronting him publicly, and pressuring French and Bolivian governments into extradition. Archival footage, wartime documents, and interviews trace the case from Lyon's occupation through the Klarsfelds' campaigns of exposure and lobbying to Barbie's eventual 1987 trial in France. The film treats the couple's methods, part investigation, part public shaming, as their own kind of postwar justice, operating where official channels had failed or looked away. It closes with the trial itself, the first in France to prosecute crimes against humanity, and the reckoning it forced with collaboration and complicity.