Nanny McPhee has a promising premise: Seven unruly children get their comeuppance from a hideously ugly Mary Poppins figure, complete with warts, a snaggletooth, and a unibrow. Nanny McPhee has quite a talented cast, including Emma Thompson, practically unrecognizable in the title role, as well as Colin Firth, Angela Lansbury, Imelda Staunton, and even Thomas Sangster, that lovestruck kid from Love Actually. To top it off, Nanny McPhee’s screenplay was written by Thompson herself, who is, by all accounts, a thoroughly smart cookie and no stranger to excellent screenplays. So why is Nanny McPhee such a disappointment?

We’ll start with the opinion of a five-year-old I overhead following the screening. “That was really bad,” he announced to the entire men’s room. Our restroom correspondent is on to something. The elements of McPhee that appeal to young children—the food fights, the outrageous magic, and the pranks—are sparse and remarkably subdued. They seem grounded in the rules of adult movies, never allowed to take off into the imaginative surrealism that is the hallmark of great kids’ movies. Take, for example, the unseasonable snow that Nanny McPhee calls down from the sky. The kids in the movie seem awfully excited about it, but the kids in the audience were less than impressed. It’s just snow, right? Big whoop. We see that all the time.

For the adults, the movie is not only unsatisfying but a little creepy. So, a nanny appears out of nowhere and is given full responsibility for a bunch of unruly children. That’s standard territory. But since when is it OK for the heroine nanny to control the children’s actions and thoughts? Mary Poppins’ magic was limited to aiding Jane and Michael’s dreams. McPhee is in another game entirely, teaching “lessons” by way of creating a family of automatons. The inevitability that the children come to love her is out of place here. McPhee is the ogre and the characters are too smart to miss that.

We expect an austere exterior, obviously. That’s what the warts are for. Come to think of it, that’s what many fairy tales are about: inhabiting a world of larger-scale good and evil forces. Disney often edits out the nasty bits of fairy tales. A movie like Nanny McPhee should come along to remind us that we kind of enjoy stories about a Britain of querulous servants, oppressive social norms, and the constant threat of the work house for financially insecure families. But the nanny herself isn’t supposed to be one of those controlling forces. She is supposed to mitigate them. I suppose that at this point, fans of the movie will accuse me of taking a simple story too seriously. But I wonder what else I am supposed to think when Nanny McPhee puts thoughts into the children’s heads by way of telepathy and then claims that a lesson has been taught. It left me feeling unsettled.

Even if this is just a light-hearted farce, it betrays us in the third act with one of the sappiest endings ever filmed, complete with last-minute admissions of love, a great deal of severe family togetherness, and the aforementioned magical snowstorm. Whose fantasy is this, exactly? The children are probably more concerned about the fate of the grotesque dancing donkey (looking about as convincing as the dancing baby in Son of the Mask) than they are about the fate of Colin Firth’s love life. For adults, it is no better; it feels like being sandblasted with sugar-coated maple syrup with sprinkles on top. No tear is left unjerked.

Nanny McPhee should have been good. It should have been off-the-wall enough to entertain the kids and intelligently humorous enough to entertain the adults. Instead, it is subdued then sappy, a dull introduction followed by a slap-in-the-face Valentine’s Day card. Thompson, Firth, and the rest of the cast are all up to the task. It is especially disappointing to see them fall flat with such a poorly conceived screenplay.