Marla Olmstead paints ferocious, bold abstractions that convey the joys, sorrows and fears of existence. She has an agent and solo exhibitions in glamorous galleries, cruises in limos and boasts work that sells for tens of thousands of dollars. Her other accomplishments include teething, learning to pee in a toilet and successful bipedal motion. Marla is a Renaissance toddler. Marla is 4 years old.

Or at least she was 4 when she first burst onto the art scene. That's when filmmaker Amir Bar-Lev began documenting her meteoric rise (she's now 7). The fruit of Bar-Lev's efforts is My Kid Could Paint That, an engrossing film that begins as an endearing tale of a miraculous little girl, an exploration of the fascination with "child prodigies" and a musing on the status of modern art, but quickly becomes a far more unnerving tale of greed and manipulation.

Documentary filmmaking is as much luck as it is talent, and Bar-Lev is gifted with both. Fortune shines brightly on his characters, who could have been much plainer. There's Marla, the cherubic, ultra-innocent calm at the center of the storm; her mother, Laura, protective maternal instinct incarnate; and Marla's father, Mark, who works a schedule opposite Laura and seems to also have the opposite parental impulse.

But the most astonishing character by far is Anthony Brunelli, the Olmsteads' art dealer and agent. It's hard to believe Brunelli is real. He comes across as a Christopher Guest character, so surreally slimy are his shifty eyes, his salesman twaddle, his fatuous descriptions of his own motivations.

Bar-Lev also makes use of a few talking heads. Chief among them are Elizabeth Cohen, a columnist at a local paper in the Olmsteads' hometown, who introduced Marla to the world and to The New York Times' chief art critic, Michael Kimmelman.

Kimmelman explains the public fascination with Marla as the result of a general skepticism with modern-and particularly abstract-art. Bar-Lev intersperses Kimmelman's comments with amusing stock footage of donkeys painting "abstracts" with their tails.

Both Kimmelman and Cohen, in turn, aim their criticisms back at Bar-Lev, who, in a clever bit of meta-criticism, leaves their comments in and uses them to redirect the film in on itself. Cohen accuses Bar-Lev of exploitation and opportunism (even as she continues to write Marla columns). Kimmelman goes all Postmodern Literature 101 on Bar-Lev and suggests that however his film turns out, it will itself be a construction and "a lie."

But can Bar-Lev's reflexivity absolve him? Opportunism, and the clever forms of denial that are always its handmaiden, lurk everywhere in My Kid. So incessant are the reminders, here and everywhere, that innocence, like childhood, is fleeting and, once gone, it's never to return.