More often than not, the Disney formula succeeds, so it takes courage for the studio to back a film like “Atlantis: The Lost Empire,” which does away with almost everything viewers expect. There are no musical numbers or cute sidekicks. The hero is an adult. The villains are not immediately obvious. It has a PG rating. There are even subtitles.

Basically, this is an adventure film, inspired by Jules Verne and aimed well above the heads of the preschool crowd. Set in 1914, “Atlantis” tells the story of Milo Thatch (voiced by Michael J. Fox), an eccentric linguist whose grandfather was an expert on the fabled lost continent. The old man was a laughingstock because of his theories, and Milo’s obsession with the subject has derailed his career, too. That is, until he meets Preston B. Whitmore (John Mahoney), an old colleague of his grandfather’s, who presents him with a mysterious book that could provide the key to finding Atlantis. Whitmore is prepared to finance an expedition, providing equipment and a top-notch crew, and a thrilled Milo jumps at the opportunity.

Whitmore has built a huge, state-of-the-art submarine, and Milo joins his fellow explorers, which include a ragtag group of mercenaries whose expertise is as dangerous as it is helpful. After escaping a terrifying deep-sea creature, the crew reaches Atlantis, a near-paradise that has somehow survived under the ocean for centuries. Milo is enchanted by the place, and with the help of the Atlantean princess, Kida (Cree Summer), he unlocks its mystical secrets and fights to protect it from harm. There are really two movies going on here, and they don’t fit together very well. The beginning and end of “Atlantis” are old-fashioned, Saturday-matinee action material, with fights, explosions and even gunplay (remember, PG rating). Even the animation is distinctive, with a sharp, stylized look heavily influenced by comic book art.

The middle sequence, however, is a bizarre blend of anthropology and New Age gibberish, with a softer, more traditional appearance. The film’s creative team, which includes directors Kirk Wise and Gary Trousdale, producer Don Hahn and about a dozen writers, uses the idea that Atlantis was the foundation for all other human cultures. Every aspect of the Atlantean world, from language to art to religion, looks and sounds vaguely familiar, without being directly connected to any one civilization. This approach adds a level of sophistication to the material that will certainly interest Atlantis buffs, and may well capture the attention of the more imaginative kids in the audience.

There has to be some explanation for the empire’s continued underwater survival, though, and that’s where things get strange. In fact, it’s virtually impossible to describe; it has something to do with giant masses of energy, ancestor worship and crystal power. It actually makes sense while you’re watching it, but good luck explaining it to anyone later, especially young children.

This movie isn’t really for young kids, anyway. They might enjoy the gorgeous scenery and moments of silly humor, but the action is pretty intense and the plot is just this side of nonsensical. There are no lines or characters that really stand out and grab your attention — it’s unlikely that the tykes will be clamoring for a Milo Thatch action figure.

Even older viewers might find themselves getting bored when the monsters and crystals aren’t on screen, and they have a right to expect better from the studio that created masterpieces like “Pinocchio” and “Beauty and the Beast.” Pumped-up adventure scenes and mythological musings are great, but they need a decent script to hold them together. While the folks at Disney should be commended for shaking up the old formula, they shouldn’t forget why they used it in the first place.

**1/2

‘Atlantis: The Lost Empire’ is rated PG.