For the first 20 minutes, "Miss Pettigrew Lives for a Day" looks pretty grisly. Frances McDormand and Amy Adams - talk about four big saucer eyes! - push and mug and generally act like they're in a second-rate production of a 1930s English farce, and the way they scale their effects, it's like watching performers aim for the second balcony while you're sitting in the front row.

But then everything calms down, and the film stops trying to eat you alive with its door-slamming antics. By the end of "Miss Pettigrew," an artificial construct full of familiar comic archetypes has relaxed into a charming Cinderella story. What does this prove? Only that some entertainments do recover after a bad start.

The film comes from a 1938 novel by Winifred Watson, one of six books the Newcastle resident wrote before the end of World War II. It's pure froth, and while screenwriters David Magee and Simon Beaufoy have tarted it up a bit (male dorsal nudity, a few discreet bait 'n tackle jokes) they respect the tightly compressed 24-hour time frame and Watson's atmosphere of Deco swank and romantic possibility.

McDormand plays a virginal middle-aged governess ("the governess of last resort") who connives her way into a job as social secretary to a flighty, beau-juggling singer in London. The character has been Americanized for the film; she's played by Adams.

Life is busy for the Adams character, named Delysia Lafosse. She's stepping out with the son (Tom Payne) of a theatrical impresario who's putting on a new West End show, "Pile on the Pepper," and Delysia is banking on the casting couch leading straight to the leading-lady perch. She's also keeping company, as well as a gorgeous apartment (designed to the nines by production designer Sarah Greenwood), with the thuggish owner (Mark Strong) of a nightclub where Delysia sings.

Solid, sane Miss Pettigrew helps Delysia sort out her men and focus on the one who's The One For Her, a piano player (Lee Pace of "Pushing Daisies"). Pettigrew, meantime, attracts the attention of a dress designer (Ciaran Hinds). The film flits from apartment to nightclub to fashion show and then back to the apartment, like a play. It's all highly, even shrilly theatrical. Yet once the performers take it down a notch and the workmanlike direction by Bharat Nalluri stays out of the way, "Miss Pettigrew Lives for a Day" makes you forget that the roles played by McDormand and Adams - both of whom have done wonderful things in other movies - probably could've been handled with more finesse by, oh, several dozen other performers, English or American. Style is a tricky, elusive thing, and this film doesn't so much have it as strive for it, constantly. But something in Watson's story endures: The wish-fulfillment truly satisfies. And with the war clouds gathering by story's end, the fairy tale acquires a bittersweet edge, nicely cutting all that whipped cream.