According to the director of 51 Birch Street, Mike and Mina Block are “hardly people you’d think of making a documentary about.” He should know: Doug Block is their son. And he went ahead and made a film about them anyway. Block first videotaped his parents merely for posterity, but when his mother unexpectedly died in 2002—and his 83-year-old father then just as unexpectedly married his former secretary—he began piecing together a portrait of a marriage, Capturing the Friedmansnstyle. Dad’s remarriage, while shocking, isn’t the only thing that inspired Block to turn the story of their 54-year partnership into a movie, though—Block’s mother may have no longer been around to talk to her son about her life, but she left behind 35 years’ worth of journals, faithfully kept. 51 Birch Street is engrossing and uncomfortable, often offering stomach-twisting honesty about the true feelings behind the couple’s photographed smiles. Block’s relationship with his still sprightly father was never very close, and Block père doesn’t exactly spill his guts about his marriage to Mina, or what, if anything, went on with his new wife, Kitty, 30 years ago. But Mina’s ruminations are aching, revealing inner turmoil and pretense that are scandalous if only because they occurred in seemingly ordinary lives. (Especially interesting are her insights about being a housewife in the straitjacketed ’50s and turbulent ’60s.) Block, who never suspected any unhappiness growing up, seeks unknowable answers from his sisters, a friend of Mina’s, and even a therapist and rabbi (both useless) as reality sinks in. The project then becomes autobiography, with Block examining his own marriage and feeling of contentment in a new light. The triumph of 51 Birch Street is that, as you’re driving home past fast-food joints and strip malls, you’ll be thinking about your own life as well.