In “The Wizard of Oz,” Frank Morgan’s titular character reveals little about his background except for these provocative lines:

“I’m an old Kansas man myself. Born and bred in the heart of the Western wilderness.”

So Dorothy and the Wizard — the two mightiest outsiders in the realm —were both Kansans? Quite a coincidence. How did that happen?

Disney’s new epic “Oz the Great and Powerful” fills in the gaps of how a Midwest con man manages to wrest the Emerald City from some very wicked witches. It doesn’t attempt to slavishly replicate or radically re-imagine the classic 1939 film, instead finding its own voice within L. Frank Baum’s established mythology. The result is a long but enjoyable family adventure that is as noisy as it is clever.

Predictably, “Oz” begins in cropped black and white, with a title sequence that simulates old-timey stereoscopes. From there we meet Oscar Diggs (James Franco) — Oz to his friends — a circus magician in turn-of-the-last-century Kansas. While the handsome performer is primarily a sleight-of-hand/smoke-and-mirrors guy, he’s most fascinated by technology.

“I want to be Harry Houdini and Thomas Edison all rolled into one,” he claims.

One balloon ride within a tornado later, he’s deposited in the Land of Oz, where he’s immediately championed by the lovely young witch Theodora (Mila Kunis). She and worldlier older sister Evanora (Rachel Weisz) believe him the same Oz prophesized to vanquish the Wicked Witch and bring peace to the kingdom.

But who exactly is this villain?

Oz picks up a few confidants along the way, including a flying monkey in a bellhop uniform named Finley (voiced by Zach Braff, who gets the flick’s best lines) and the delicate porcelain China Girl (voiced by Joey King, who represents its best special effect).

He also allies with Glinda (Michelle Williams), a bubble-conjuring witch who spots him as a phony right away. But she realizes that the people’s belief in a faux wizard might be more valuable than actually having a true wizard.

If Franco isn’t exactly tailor-made for the lead (it’s easier to picture Robert Downey Jr. or Johnny Depp —both of whom bailed on the role), he at least gives it his A-game. No one will argue that his performance as Oscar is better than his Oscars hosting performance.

His character’s smug charm may work wonders onstage, but it proves woefully inadequate against the foes dispatched to destroy him. This makes him more relatable, and it gives the movie a genuine sense of danger. How will the hero succeed?

Folks tend to forget that “The Wizard of Oz” is one very intense, very scary children’s movie. There are equally nightmarish moments in the prequel’s Dark Forest. And when the true witch is finally revealed, she’s just as alarming as a lime-green Margaret Hamilton.

Director Sam Raimi found his comfort zone doing horror with “The Evil Dead” trilogy before going mainstream in the first “Spider-Man” franchise. His darting camera and eccentric throwaway gags are on full display here. Other Raimi touches: the “Deadite” mannerisms of the witch (who also sports a good dose of Green Goblin in her jawline) and the Dr. Octopus-style tentacles that attack the heroes in the forest.

Yet Raimi gets reined in a bit. One might say Disneyfied. He’s forced into some hokey P.C. choices to secure a PG rating. These are most blatantly on display during the clumsily staged crowd scenes, where retroactively desegregated citizens of Oz look like creepy Hummel figurines come to life. And aside from Finley and China Girl, the other supporting players are either forgettable or distracting.

Tony Cox (so hilarious as the foul elf in “Bad Santa”) is particularly awful as the Munchkin herald Knuck. Veteran Bill Cobbs as the MacGyver-like Master Tinker is similarly underused. By the end, these men are positioned in a lineup as if they’re as crucial to the Wizard as the Scarecrow and Cowardly Lion were to Dorothy. However, the audience has barely gotten to know them.

While the first hour and a half of “Oz the Great and Powerful” moves assuredly, the last act crawls once the plot intricacies are revealed. The wonders start to wane, and the movie’s colorful, vibrant impact fades to sepia tones.