There's no reason Nanny McPhee shouldn't be a fine children's movie. Based on Christianna Brand's beloved Nurse Matilda books, and adapted capably by Emma Thompson, who plays the lead, the film positions itself nicely as the anti-Mary Poppins. It takes a darker route to the same magical lessons about behaving well and running a tight ship. From top to bottom, the cast couldn't be more appealing, with minor roles filled out by ringers like Vera Drake's Imelda Staunton and a gleefully imperious Angela Lansbury, and a gaggle of child actors who aren't the usual snot-nosed noisemakers from central casting. And yet there are times when Nanny McPhee seems designed to drive all but the most sugar-crazed spazzes out of the theater: Colors that should never go together clash like a tempest, the camera whisks around in manic curlicues, and a musical score makes certain that nothing magical goes underemphasized. It's as if the filmmakers' prevailing philosophy was that kids would like everything adults hate.
The film opens with a nanny fleeing in terror from a chaotic household; she's the latest in a series of caretakers victimized by seven naughty children acting out after their mother's death. Their father Colin Firth, a weak-willed mortician, has already run through 17 nannies, few of whom lasted more than a day. He needs a miracle to bring his kids into line, and one arrives in the gnarled form of Emma Thompson, a witch-like governess with hideous features, including a pair of hairy moles, a unibrow, a tooth hanging over her bottom lip, and a nose on loan from Karl Malden. With her magic walking stick, Thompson instills discipline by way of irony: For example, when the kids feign sickness in order to stay in bed, she gives them the measles and makes it physically impossible for them to leave their beds. Meanwhile, Firth has a month to find an acceptable wife, or else his benefactor (Angela Lansbury) will cut off his allowance and send the family to ruin.
The sinister impulses of Roald Dahl have a clear influence on Nanny McPhee, but director Kirk Jones (Waking Ned Divine) consistently confuses garish for dark, which takes away much of the nanny's edge. Nicolas Roeg's superior adaptation of Dahl's The Witches employs a baroque style that heightens the intensity and menace without going over the top. Nanny McPhee falls back on the Nickelodeon principle "If all else fails, hit 'em with a retina-searing overload of visual and aural information." Perhaps tykes have the energy to process it all, but other systems are destined to eventually shut down.