There’s a yellow brick road waiting to guide Oscar (James Franco) — Oz to his friends — and his companion to the Emerald City. (Walt Disney Studios Motion Pictures)

If you go see “Oz the Great and Powerful,” you’ll most likely be handed 3-D glasses, the better to appreciate an expensive, lavishly produced special effects extravaganza and plop a few more dollars into Disney’s coffers. But you’ll need to supply your own air quotes.

A healthy sense of irony is needed not only to stomach the title — the shifty, wispy protagonist of this “Wizard of Oz” prequel is neither great nor powerful — but also for most of the production, which constantly falls short of the inflated expectations it has set up for itself.

Starting with a woefully miscast James Franco in the title role, continuing through a lame story line that’s merely a warmed-over version of the 1939 movie adaptation, and extending to visual effects that never approach the dazzlement and wonder of its revolutionary forbearer, “Oz the Great and Powerful” is a big, over-processed misfire that with a little more care and ingenuity might have lived up to its name.

When “Oz the Great and Powerful” opens, Oscar Diggs (Franco) is working as a sideshow conjurer with a traveling circus in 1905 Kansas, captured, fittingly enough, in the black-and-white, square-framed format of old-timey cinema. After an interminable, sludgily paced opening sequence during which Oscar (a.k.a. “Oz”) breaks hearts and mistreats his faithful assistant, Frank (Zach Braff), he’s forced to make a quick escape from the midway via hot-air balloon, at which point he’s caught in a cyclone that plops him down in a brightly colored, wide-screen world of enormous, psychedelically hued flowers, mysterious forests and a crystalline city made entirely of emerald.

If that all sounds familiar, it’s meant to: “Oz the Great and Powerful” hews faithfully — some might say slavishly — to Victor Fleming’s “The Wizard of Oz,” this time casting the man behind the curtain as the outsider who embarks on a heroic quest with the help of friends he makes along the way. In Oz’s case, these are a flying monkey named Finley (voiced by Braff), a delicate painted china doll (Joey King) and, eventually, a witch named Glinda (Michelle Williams), who enlists Oz to help her fight her evil counterpart, Evanora (Rachel Weisz).

Oz also meets a witch named Theodora, played by the always-fetching Mila Kunis in a performance that, for an actress who has shown such spirit and verve in previous films, seems strangely un-focused and inert here (at least initially). Admittedly, Kunis doesn’t have much of a partner in Franco, whose laid-back, half-mast coolness bears no resemblance to the manipulative sharpie Oz is supposed to be. When Franco says the word “prestidigitation” behind his stoner’s grin, it’s as if he’s uttering it for the first time in English class. Time travel may be one element of the L. Frank Baum stories on which “The Wizard of Oz” and this incarnation are based, but plopping a Gen-X California boy into a role that calls for swift instincts and shrewd alertness is an error from which “Oz the Great and Powerful” never recovers.

The same could be said for a story that, as written by Mitchell Kapner and David Lindsay-Abaire and directed by Sam Raimi, feels like little more than an afterthought, a lame attempt to cash in on the enduring appeal of “The Wizard of Oz” without providing any genuine imagination or innovation of its own. As Oz and his motley band travel down the Yellow Brick Road, Raimi punctuates their journey with nods and references to the classic “Oz” film, introducing a fierce lion, an army of scarecrows and a field full of horses of a different color along the way (not to mention Munchkins and Winkie Guards). But what’s meant to be an affectionate, clever way of establishing continuity between the two narratives instead serves to remind viewers of the enduring superiority of the classic.

As an origin story, “Oz the Great and Powerful” comes up with some interesting theories, especially having to do with the Wicked Witch of the East and her green-skinned sister. But mostly, this movie seems designed merely to up an already bloated special-effects ante, from the now-30-percent-more-terrifying flying monkeys to a prolonged, explosive climactic sequence.

Aside from some lyrical moments early on when flames and birds dart out of the sides of the frame, 3-D technology adds little to an underwhelming endeavor. Like “John Carter” last year and “Jack the Giant Slayer” last week, “Oz the Great and Powerful” qualifies as a cautionary tale, not about the perils of ambition and selfishness, but about the movie industry’s misguided belief that it can distract the audience from a film’s narrative weaknesses with little more than flash and spectacle. That con might have worked with the rubes once upon a time, but in case Hollywood hasn’t noticed, we’re not in Kansas anymore.

PG. At area theaters. Contains sequences of action and scary images and obscenity. 130 minutes.