Charlize Theron (Monster) takes on another unglamorous, lived-in role in this profound and riveting character study of a mother who’s at the end of her tether. Severe postpartum depression. No, desperation. Marlo’s got a newborn, two other kids, one autistic, and an oblivious husband. To stay sane, she reluctantly accepts as a gift from her rich brother the services of a “night nanny” named Tully (Mackenzie Davis, excellent), who turns out to be thoughtful, wise and a little mysterious, and Marlo’s life is turned around. The movie cheats a bit on the Big Reveal, but in a good way. The director of this irreverent, insightful and even darkly funny film is Jason Reitman, and the writer is Diablo Cody, both doing their best work since Juno. (95 min)