"Keeping Mum," a British black comedy, saves its best for last -- and God bless Maggie Smith for, well, being Maggie Smith -- but that requires sitting through a frustrating, uneven hour of sluggish preamble.

Rowan Atkinson plays the Rev. Walter Goodfellow, a British vicar too lost in his spiritual calling to realize that his wife, Gloria (Kristin Scott Thomas), is one sexually frustrated camper, that his young son (Toby Parkes) is getting beaten up at elementary school and that his 17-year-old daughter (Tamsin Egerton) is having sex with anyone who so much as makes the request.

Along comes new housekeeper Grace Hawkins (Smith), a sort of avenging Mary Poppins who -- unbeknownst to the family -- sliced and diced her husband and his mistress more than 40 years ago. Immediately perceiving everyone's mutual needs, she makes an immediate impact on their lives, as only a sweet-natured murderess can.

Atkinson's bumbling parson act -- which he already exploited in "Four Weddings and a Funeral" -- seems phoned in. And screenwriters Richard Russo ("Nobody's Fool") and Niall Johnson (who directs) are never sure what tone to take. Despite her frustrations, Gloria's extramarital dalliance with lecherous golf instructor Lance (Patrick Swayze at his tanned and crinkliest) seems bizarre, even for a dark comedy. And when Lance ogles Gloria's daughter through binoculars, we have to wonder why the audience is given a nice long look as well. These and other discordant notes make the sardonic third act an immense relief for the wrong reasons.

-- Desson Thomson (Sep. 29, 2006)

Contains grisly comic violence, profanity, nudity and sexual content.