Documentary about the life of the photographer Francisco Boix (Barcelona 1920 – Paris 1951). After the Spanish Civil War, exile took him -along with 7,000 other Spaniards- to the Mauthausen concentration camp. There he was assigned to the photographic laboratory, from where he took more than 2,000 photographs in an operation of resistance unheard of in the history of Nazi repression. After the liberation, Boix contributed some of these photos to the Nuremberg Trial as evidence against important members of the military leadership of the Third Reich.