Every reader of Anne Frank’s diaries knows her father Otto as “Pim,” but his role in the book extends far beyond the Amsterdam attic. Otto was the only Frank to survive the Holocaust, and after the war he dedicated his life to the diaries, working tirelessly to ensure the book’s status as one of the 20th century’s signal literary testaments. David de Jongh’s documentary draws upon a wealth of archival footage and interviews to fashion a sympathetic but complex portrait of a man driven by pride and grief. The film traces Frank’s old-world deference back to his early years as an assimilated German Jew and details his obsession in maintaining Anne’s memory. His correspondences with young readers are especially revealing: He answered every note personally and went to great lengths to encourage readers’ identification with Anne, going so far as to sign certain letters “Pim.” De Jongh interrogates Frank’s misleading claims that he merely proofread Anne’s original diaries and weighs the still controversial brightening of the original material for a smash Broadway production and film. Frank’s zeal to promote the diaries led him to questionable compromises and interpretations, but as de Jongh’s evenhanded film makes clear, Anne’s diaries are unthinkable apart from Otto’s devotion.