Here’s a fun idea: Tell the “Little Red Riding Hood” fairy tale “Rashomon” style, with each participant — Red, Granny, the wolf and the woodsman — giving his or her version.

Now here’s a stupid idea: Do that, and then drag the story out for an additional half-hour by including an elaborate backstory that requires a complicated resolution.

“Hoodwinked” takes the stupid path through the forest, doing serious damage to what was otherwise a fairly amusing animated film. Written and directed by Cory and Todd Edwards, brothers who are making their big-time debut with this Weinstein Co. release, the film will probably provide adequate delight to the youngsters, but it overstays its welcome too much for more discerning viewers.

It begins at the climax of the familiar Red Riding Hood story, with Red (voice of Anne Hathaway) questioning the Wolf (Patrick Warburton) about the size of his hands, teeth and ears (“All the better to hear your many criticisms”), and the subsequent rescue by the Woodsman (James Belushi). Granny (Glenn Close) was tied up in the closet all along.

The forest police arrive and cordon off the crime scene. The cops and detectives are animals; the Three Little Pigs are uniform cops, while a bear is chief of police. Inspector Nicky Flippers (David Ogden Stiers), a frog, shows up and says all of this could be part of a larger case. Granny runs a highly profitable “goody” business (cookies, pies, etc.), and many of her competitors have recently had their recipes stolen by the so-called Goody Bandit. Is Red, the Wolf, Granny or the Woodsman the culprit? Or is it someone else altogether?

As each character gives his or her account of the facts, the film cleverly doubles back and weaves the story into the bigger picture. For example, we wonder why Granny appears in a “vision” in Red’s story; later, when Granny’s story is told, we see why. It’s a fun device, and the movie’s happy-go-lucky attitude keeps everything light and frivolous.

Then there’s a problem. All four characters have testified, and we still don’t know who the Goody Bandit is. Another act is required to tie things up, and that’s where the story becomes burdened with details and subplots. Red has a lame conflict with Granny when Granny’s secret life as an extreme-sports enthusiast is revealed. (Is the idea of a sweet old lady doing “young” things even funny anymore?) The upside is that Red gets a song, and it’s performed by the marvelous Ben Folds. (In fact, the film’s catchy pop-rock soundtrack is generally above-average.) The downside is that the film keeps going, far longer than it ought to before finally ending.

The computer animation is not exactly state-of-the-art. The characters are drawn puffy and bulbous, and they move the way video-game characters did in the late ’80s. It all seems too mechanical, not at all realistic the way we’ve come to expect from computer-animated films.

The technical deficiencies could be overlooked if the story were great, but it’s merely average. It has laughs, and smiles, and a couple memorable characters (Twitchy the hyperactive squirrel and Japeth the singing mountain goat, specifically). But it doesn’t have enough of any of those things. And that drawn-out finale…! Can’t we just let these people live happily ever after?!

C+ (1 hr., 20 min.; PG, mild whatever and stuff; it's a kids cartoon.)