Is anything more dispiriting than a failed attempt at inspiration? Brad Bird’s Tomorrowland starts with Spielbergian promise, full of mystery, awe and a childlike sense of adventure. At the 1964 World’s Fair, a self-possessed country boy named Frank Walker (played at 12 years old by Thomas Robinson and later in life by George Clooney) shows off a homemade jet pack that he hopes will win him an inventor contest.

Alas, unlike young Buddy in Bird’s The Incredibles, whose rocket boots really worked, Frank’s jet pack isn’t quite ready for prime time. In any case, a hard-nosed judge (Hugh Laurie) is no more sympathetic to Frank than Mr. Incredible was to Buddy. How would his jet pack make the world a better place? It would be fun, Frank answers, and would inspire people to believe that anything is possible. Well, perhaps it would — if it worked.

Frank is disappointed — but his consolation prize is beyond all expectations. A mysterious girl named Athena (13-year-old Raffey Cassidy) with a posh English accent gives him a gentle push in the right direction, and Frank intrepidly follows her down the rabbit hole into the world of his dreams: a Tomorrowland world where anything goes, even his jet pack.

Then the movie returns to present-day reality, or something like it … and, over the next two hours, it turns out that Tomorrowland is a lot like Frank’s jet pack: something meant to be fun and to inspire people to believe that anything is possible, even though it doesn’t really work.

Perhaps Athena was right to feel that young Frank deserved credit for effort; I expect much more from Bird, the director of three of my favorite animated films, not to mention my favorite Mission: Impossible film. Not to let Bird off the hook, but surely screenwriter Damon Lindelof is a big part of the problem. Tomorrowland exemplifies what is increasingly becoming Lindelof’s trademark: early sizzle and a great sense of promise dissipating by the disappointing third act (see: Star Trek Into Darkness, Cowboys vs. Aliens, Prometheus and perhaps Lost, unseen by me).

Tomorrowland argues that the future is as dark or as bright as we choose to make it; that artists, scientists and dreamers can save the world; that the dystopian post-apocalyptic nightmares dominating popular culture are killing us and are no more inevitable or realistic than the Space-Age techno-optimism of Disney’s Tomorrowland and EPCOT, Roddenberry-era Star Trek and even The Jetsons. I’m all in favor of these ideas, but if Bird of all people can’t make them more compelling, there’s no reason George Miller should ever retire Mad Max.

The real protagonist of Tomorrowland is not Frank, but Casey Newton (Britt Robertson, 25, but playing younger), a dreamer who lives in a present-day world in which the dreams of the Space Age are being abandoned and dismantled. Casey’s father is a NASA engineer slated to be laid off when the launch platforms at Cape Canaveral have been disassembled — a project Casey sabotages each night, partly out of nostalgia for the space program and partly to prolong her father’s employment. Like young Frank, Casey is unexpectedly, inexplicably heralded by a shining vision of the future — but unlike Frank, she can’t get into that world, with sometimes amusing results. When she goes in search of answers, she gets more than she bargained for: She’s attacked, rescued, chased, abandoned, left out in the cold, attacked again, rescued again, chased some more and eventually goes farther than she ever thought possible. At some point, she’s thrown together with grizzled, disillusioned old Frank Walker, whose Tomorrowland adventure apparently ended badly. Athena’s still around, still 13, and she and Frank don’t get along.

Bird is a master of action set pieces, as The Incredibles and Mission Impossible — Ghost Protocol amply attest, and he makes this stuff diverting enough. A siege at Frank’s house, in particular, is excitingly well-staged and full of inventive touches.

But it’s all just diversion — just the plot spinning wheels until it’s time for the third act. None of this has anything to do with Tomorrowland or the threatened dystopian alternative. There are scary robots whose casual disregard for human life (more than once they vaporize inconvenient police officers or guards) may not be satisfyingly accounted for once it’s revealed who they’re working for and what his motivations are.

When that revelation occurs, Tomorrowland falls apart badly. There have already been intimations that the movie is about the literal power of positive thinking: Optimism about the future and a belief in our capacity to change things can actually exert a transforming effect on the world. Over and over we’re told what a special person Casey is, and her hopeful outlook is clearly a key part of her specialness, along with her intuitive understanding of “how things work.” In the end this half-baked humanism mutates into something more egregious. I have nothing against the film’s message that cynical pop culture is killing us, or that we’re better off feeding our hopes and dreams than our fear and despair. The problem is the way Tomorrowland ultimately becomes a message-driven tract or public service announcement. It’s almost a kind of secular faith-based film — call it Tomorrow’s Not Dead — with its faith in special people doing inspiring things.

Ironically, the climax turns not on anything inspiring or creative, but on standard action-movie shooting, explosions, giant robots and a Marvel-movie MacGuffin, a black box of badness we’ve got to destroy before it does the bad thing it does. In the clinch, it turns out that Casey’s specialness doesn’t really matter; neither her optimism nor her understanding of how things work is crucial to fixing the problem.

Instead, the focus returns to Frank and Athena, and here things get awkward: Clooney is playing a character whose heart was broken as a young boy by a girl who is still played by 13-year-old Cassidy. Didn’t anyone making this movie notice that their tender final scene is at least borderline creepy? (If it’s still a spoiler at this point to say it, it’s yet another tale of a human male falling in love with a female A.I., along with Ex Machina and Her.)

In the very end (spoilers, obviously), the movie flings its arms open wide, embracing all the dreamers of the world of every kindred, tongue, people and nation, inviting them all to the promised land, a multicultural paradise on earth looking a bit like a painting in a Jehovah’s Witnesses tract.

What’s a little condescending is the way people of color are deemed worthy to play in the sandbox only after the white protagonists have saved the day. More troubling is the way the emphasis on “specialness” — a notable theme in both of Bird’s Pixar films — plays out here. In The Incredibles and Ratatouille, those with gifts used them because they found fulfillment in doing so, but also for the benefit or the appreciation of ordinary people. Mr. Incredible saves ordinary people who really need saving, and Remy prepares food that people really enjoy.

In Tomorrowland, there’s talk about saving the world, but all we actually see onscreen is a solidarity of artists, scientists and dreamers called to live apart from common folk in utopian creative freedom. For years some have raised questions about an Objectivist, Ayn Randian vibe in Bird’s movies: a preoccupation with special people and an indifference to ordinary people. That never struck me as a plausible critique of any of his films — until this one.

Steven D. Greydanus is the

Register’s film critic.