By the time we got to Toronto, speculation about Marielle Heller’s “Nightbitch” had reached fever pitch. Would the film, adapted from Rachel Yoder’s novel of the same name, be Amy Adams’s vehicle for an Oscar win after six unsuccessful nominations? Or would it be a misguided, tonally discordant mess with a title that would inspire a thousand dog puns? “Nightbitch” works largely because of Adams’s agile, gutsy performance as an artist-turned-stay-at-home mom who puts her once-promising career on hold to care for her adorable but rambunctious toddler. (Her character, who is never named, is credited as “Mother.”) Her well-meaning but clueless husband, played by Scoot McNair, travels frequently for work, leaving her at home to fend for herself and whip up countless pots of macaroni and cheese. Exhausted and resentful, she begins to notice strange physical changes: a heightened sense of smell, a patch of hair on her back. “Nightbitch” is a surreal, insightful film about the joys and heartbreaks of motherhood and the sometimes disturbing ways in which becoming a mother can transform women’s minds, bodies, emotional lives and entire sense of self. It won’t be for everyone, but then again, neither is being a father. Blake