It's helpful to think of "Wendy" as a child's bedtime story — not one told to a child, but by a child.


For that is, quite literally, what it is: a fable sprung from the imagination, hopes and fears of a little girl, in this case the title character (Devin France), who is very loosely based on the Wendy Darling of J.M. Barrie's "Peter Pan." Her voice-over narration crops up throughout this dreamlike tale of escape and responsibility-shirking to remind us that the narrative vision is shaped by the voice of a novice storyteller. That means it is inconsistent, at times downright illogical and contradictory and yes, sometimes even poetic.


Directed by Benh Zeitlin ("Beasts of the Southern Wild") — who co-wrote the screenplay with his sister Eliza Zeitlin — the story opens in the American South, where Wendy and her twin brothers James and Douglas, played by twins Gavin and Gage Naquin, live with their diner-waitress mother, close by a railroad track. As so often happens in proximity to trains, Wendy dreams of travel to far-off lands, and one night, or perhaps only in her imagination, she jumps from the roof of her house to a moving locomotive, followed by her brothers.


There the three children encounter Peter Pan (Yashua Mack), a charismatic ragamuffin who takes them — not by pixie dust-enabled flight but via rail, then rowboat — to a mysterious volcanic island where they also meet his band of lost boys, and one girl: Sweet Heavy (Ahmad Cage); Thomas (Krzysztof Meyn); and Cudjoe Head (Romyri Ross).


Thomas, as it turns out, is someone they already know, a little boy who went missing from their hometown several years ago but who hasn't aged a bit since. When they last saw him, Thomas was flinging off his trousers and shouting, to a passing train: "I ain't gonna be no mop-and-broom man!" — an allusion to his presumed grown-up fate.


So far so good, if also a little too faithful to the source material, and its well-worn themes. "The more you grow up," one character tells us, early in the film, "the less things you get to do that you want to." Check.


But things quickly begin to deviate from the story we all know. Part of Peter's island home is inhabited by a group of superannuated "olds" (possibly the counterpart to "Peter Pan's" pirates, but also maybe not). One of them, we're told, started to age after he lost his best friend. Loss, it seems, in the shaky cosmology of "Wendy," is what makes you age. But what kind of loss — loss of a loved one, of the self, of innocence, of hope, of the ability to believe in magic, all of which are posited — is unclear.


There is also an entity referred to as Mother, who at times seems to be an Earth spirit, or maybe the volcano, or possibly also a sea creature — part giant puffer fish, part whale — who offers a healing presence represented by an ineffable glow. It's a nice metaphor for something, but also annoyingly vague. "Mother's off the starboard port bow," someone yells, when a fishing expedition is mounted.


Um, wait a minute: starboard means right, and port is left.


The ambiguity only gets worse, in a film that, however pretty, starts to lose vital focus the further afield it drifts from "Peter Pan." There's an overarching theme of the wisdom of children, carried over from Zeitlin's "Beasts," as well as a subtle rumination on environmental threats. On one very straightforward level, "Wendy' is also kind of a Captain Hook origin story, centering on Wendy's brother James. (Don't ask how he loses his hand. It's a surprisingly grisly moment for a movie based on a book for kids.) On another level, it's an allegory of something we all go through — and, to a greater or lesser extent, all fear: aging.


But letting go of one thing allows you to embrace another. That's the real, and somewhat obvious, lesson here, in a lovely yet flawed confection that might be summed up by two words: beautiful nonsense.