A movie can't quite escape its narrators, for better or worse.

For "Manny & Lo," which tells the story of two orphaned sisters on the run, this fact becomes harder and harder to ignore, as the film is buffeted about by the tired-eyed wonder of the younger and the stilted bluster of the elder. Apart from a consistently hilarious deadpan performance by Mary Kay Place, the story remains dreamy and quirky, but, almost too faithful to its vagabond kiddie heroes, a little grating and puzzling.

Amanda (Scarlett Johansson) and Laurel (Aleksa Palladino), according to convention hereafter referred to as "Manny" and "Lo," survive through shoplifting, house-breaking-and-sleeping-in, and the liberal use of their deceased mother's station wagon. When Lo gets undeniably pregnant, the spunky pair adds a bigger crime to their misdemeanors and kidnap a staid ex-nurse (Mary Kay Place) incongruously behind the counter at one of those sickeningly precious baby supplies stores. They then hole up at an abandoned country house. Barring some frenzied running around at the end, most of the film takes place there amidst woodsy surroundings (where, inexplicably, a seemingly tropical lizard lives).

Writer-director Linda Krueger begins the film with Manny's voicing clunky, day-dreamy meditations: something about knowing someone in a dream before you meet them. The content isn't so important as the goal of drawing us into the kids' minds: wise before their years, and yet not really wise.

For about 10 minutes, the movie trundles along just fine, recovering with a shot of the two kids waking up on a suburbian lawn they mistook for a park. The automatic morning routine of the two young women is particularly touching: Manny trying to provide Lo with some privacy by shielding her.

Then the movie hits what's probably its high point, with a fine poetic juxtaposition. One day Manny refuses to play turbulent airplane to Lo's stewardess (Lo stands and balances on her, fidgeting) because she secretly fears for Lo's increasingly visible pregnancy. So in one swoop, Krueger has portrayed well the jarring, forced switch from pretend to inevitable real life.

Thereafter, things very gradually slide downhill, except for the introduction of Elaine, the ex-nurse and one or two other details. The polite reason to give would be that Johansson and Palladino play their characters a little too thoroughly.

For Johansson's Manny, this is less of a problem. With her little eye, Manny asks broadly perceptive questions worthy of a Barbara Walters interview: studying Elaine's determinedly clinical, uneasy manner, Manny declares that she doesn't think Elaine had a real family, did she. She's right, and it's a gold star for her to add to her accomplishments in admonishing Lo for her poor prepartem behavior or justly defending Elaine.

But in comparison, Lo comes across as unreasonably paranoid: throwing Elaine aside and cursing like a sailor. She isn't helped by having to toss off artificial-sounding lines about remembering who's in charge with regard to the kidnaping. And it is Lo who moves the plot along, where Manny would be content with looking at lizards.

At first glance, all this blustering about contrasted with Manny's saintly endurance can't remain appealing. We are left to puzzle over whether Krueger has intentionally created two portraits of difficult development in childhood, at two stages, one on the cusp of adolescence, the other in the throes of it: then we find ourselves more interested in the motivations and reasons behind each character's current state, more so than her actions. Or are Johansson and Palladino just stuck in their respective modes, with Palladino especially mixing playacting with the over-acting of adolescent histrionics?

Fortunately, to keep us distracted, Mary Kay Place has a hilarious turn as the eminently calm and collected adult (further skewing things). As she repeatedly declares that she has never been wrong ("Knock on wood..."), we realize that if she were just a tad overdone she could well be a secret basket case. She delivers several of the most memorable lines of the movie, lecturing to her "captors," as she calls them while serving them her signature culinary creation, known simply and ominously as "Hot Dish."

But the film's detractors acquire extra ammunition when the movie, predictably enough, swoons under a case of happy-ending fever. Confirming that the story seems on the brink of really getting interesting, Krueger pulls us away to never-never land and doesn't deal with the intriguing predicament in which the three find themselves at the end.

Separate from the story, Krueger's film technique movingly captures the tenuous string of moments that Manny and Lo enjoy on the run: hands under running water, ants scurrying like the two children.

Basically, whatever the ending, this is a film that is difficult to finish properly. We enjoy the snapshot we get of the itinerant young women's lives, precisely because it's so expressive in and of itself. But when Krueger draws out the story, it's everything Johansson and Palladino can do to continue carrying their thorough portrayals without becoming grating. "Manny and Lo" belongs to the ranks of movies that offer more pleasure in the moment's fantasy, in the little package of an idea, than in its fully realized execution.