After returning from Auschwitz, Otto Frank, the only survivor of the family, is confronted with Anne's diary. He renews ties with his daughter by reading it. The film tells the story of what he went through, how the loss of his family scarred his life, how he dealt with the dilemmas that the publication of the diary brought upon him and how he made a memorial of his daughter's legacy and became the father-figure for thousands of young readers worldwide. The film is based on unique archive material, hundreds of letters and the photo collection of the Frank family. It contains interviews with the closest friends of Otto Frank, such as his stepdaughter Eva Schloss, Buddy Elias and John Neiman.