On a train to Auschwitz, 17-year-old Heinz Geiringer told his sister Eva that he hid the paintings and poetry he had created beneath the floorboards of their attic hiding place. Heinz made Eva promise that if he should die in the camps, she would retrieve the artwork. Today, his story lives in the shadow of the Diary of Anne Frank—and in a twist of fate, Eva became Anne’s posthumous stepsister when after the war her mother married Anne’s father. While the world knows Anne’s story, this film introduces Heinz, his artistry, and his sister’s efforts to find and share his remarkable legacy.