51 Birch Street

Runs at Northwest Film Forum, Fri., Jan. 12–Thurs., Jan. 18. Not rated. 88 minutes.

Worms crawl slowly and gently out of the can in Doug Block’s marvelous home movie about the underground life of his parents’ 54-year Long Island marriage. A documentary filmmaker who—nice irony—also moonlights as a wedding photographer, Block had been capturing his family on camera for years, but Birch Street only took shape when, shortly after his mother’s sudden death, his father upped and married the woman who had been his secretary 40 years ago. On the face of it, the question for Block and his stunned sisters, as they help their visibly happy father pack up their childhood home for the move to Florida, was how long this affair had been going on. But when Block, his loving son’s guilt productively at war with his curiosity, delves into his mother’s prolific diaries, the movie grows organically into scenes from a difficult marriage his father now reluctantly admits was more functional than loving. By any measure, Mina Block was high maintenance: good-looking, endlessly introspective, and needy. An ambivalent mother (Block was very close to the woman her daughters describe as remote), she was a deeply unfulfilled suburban matron who got little understanding from her practical, uncommunicative spouse and took refuge in pot and a painfully unrequited crush on her therapist. Open-minded, probing but never prurient, Birch Street is much more than a portrait of suburban ennui. It’s a loving, painful map of the gulf between thought and word, between word and deed, that props up good marriages, and sends bad ones to hell. ELLA TAYLOR