Keeping Mum

I’ve about had it with daft comedies about daft British people doing daft British things, but “Keeping Mum” has restored my faith in the genre. This is a dark comedy, something we don’t get much of these days, and the Brits in it aren’t just daft; some of them are certifiably, dangerously mad.

A prologue informs us that 43 years ago, a young pregnant woman named Rosemary killed her husband and his mistress, chopped them up, and put them in her steamer trunk. She was captured and sent to a home for the criminally insane, which has now released her on her own recognizance, her rehabilitation apparently complete.

Now an elderly Mary Poppins type going by the name of Grace and being played by Maggie Smith, the old murderess with the steamer trunk has come to the tiny village of Little Wallop to be housekeeper and nanny to the vicar’s family. They certainly need help. The vicar himself, Walter Goodfellow (Rowan Atkinson), is a befuddled but well-meaning little man whose whole attention is devoted to his parish. His wife, Gloria (Kristin Scott Thomas), isn’t religious and is having an affair with her golf instructor, a swaggering American named Lance (Patrick Swayze) who specializes in double-entendres. The Goodfellows’ teenage daughter, Holly (Tamsin Egerton), is a wanton rebel, and her younger brother, Petey (Toby Parkes), is beset by bullies.

Within days of Grace’s arrival, the household begins to see improvements. The dog whose barking once kept Gloria awake has mysteriously stopped. The bullies no longer torment Petey. Holly starts to behave. The Reverend’s sermons even improve. Who is this delightfully gentle old woman, and what magic has she worked?

We know more than the Goodfellows do, being privy to some of Grace’s secret deeds, and there is a certain charm in a movie being so unabashedly dark with its humor. Grace has indeed killed people before, and she has no qualms about doing it again. Maggie Smith, at once matronly and scary, is perfect for this sort of thing, and her performance here makes me long to see her and, say, Judi Dench in a production of “Arsenic and Old Lace.” Wouldn’t that be perfect? Can’t you just see the two merry old spinsters toddling around poisoning people?

There are a couple developments later in the film that seem intended as surprises, though I can’t imagine director Niall Johnson (who co-wrote the screenplay with “The Ice Harvest’s” Richard Russo) thought we wouldn’t see them coming. Even as non-surprises, though, they wrap up the movie’s loose ends and give us a tidy, satisfying ending, and one that’s appropriately outrageous. No one in the film behaves the way normal people do, but that’s kind of the point. They’re not normal. Neighbors like these are deliciously fun to watch in a movie as long as you don’t have to live near them in real life.

B (1 hr., 43 min.; R, scattered harsh profanity, some nudity, some sexuality.)