In Terezín, many children sang for Nazi cadres and the Red Cross. They were used as propaganda tools, between 1943 and 1944, to make the world believe that Hitler had offered a “paradise” to the Jews… Only a hundred innocent beings out of the 15,000 passed through this transit camp survived. Ela Stein Weissberger, deported at 11, is one of the few survivors. In Hans Krása's opera Brundibár played in the camp, she played the role of the Cat, the rebellious animal who attacks the monster with the mustache, with the hope of winning the war! His poignant testimony gives voice to these courageous and hopeful children who left 4,500 drawings, journals and poems in Terezín. Like an inner road movie, the author offers a parallel story: she looks back on her own family history, her journey in search of Ela, her filming anecdotes and acts as the spokesperson for all the children targeted by hatred. . The documentary THE CHILDREN OF TEREZÍN AND THE MONSTER WITH A MUSTACHE, produced by Artisans du Film, broadcast on France 5 in La Case du siècle in 2019.