Let me get this straight. Hundreds of years from now, after humankind has fled a despoiled Earth and resettled in another galaxy where folks live in sleek high-rises with all the latest accoutrements, and where they have holographic PDAs that fold up like origami, an amputee has to hop around without the aid of an artificial limb, or even a pair of crutches?

It's a small matter in the grand scheme of After Earth, Will Smith and M. Night Shyamalan's sci-fi yarn about a young man's personal Outward Bound experience trekking across a postapocalyptic planet, but it points to the cheesy melodrama at work. When, early on in this father-and-son vehicle, a grateful veteran approaches Gen. Cypher Raige (Smith) to thank him for saving his life in the thick of battle, he insists on standing tall and saluting, shrugging off the help of two colleagues. So what if the soldier literally doesn't have a leg to stand on? We now know that the General is courageous and caring and worthy of our attention for the next hour and a half.

And, in truth, despite more corn than Mel Gibson grows on his farm in Signs (another Shyamalan effort), After Earth is worth a look. With a production design that mixes futuro-tech with a hippie Pier 1 aesthetic, this beautifully shot tale finds the superstar from Overbrook in a supporting, or at least mentoring, role, turning the action over to his son, Jaden, a rangy brooder of a boy.

The younger Smith plays Kitai, a fiercely intelligent teen determined to impress his dad - a dad who spends most of his time on extended tours of duty, busy fighting Ursas - giant alien beasts whose raison d'etre is to stalk and kill humans. They can smell fear - or the pheromones produced by scaredy-pants guys and gals - and gnash and gnaw, that's it.

But if you can face the Ursa without apprehension or dread - as Gen. Raige can - they are conquerable.

Unfortunately, when father and son Raiges crash-land back on Earth, the spaceship they've been riding - seriously dinged in an asteroid storm - is carrying an Ursa, too. Also somewhat unfortunate is the fact that the General has broken both of his legs ("one very badly," he notes) and that the SOS beacon in their wreckage has been damaged beyond use. To get the folks back on Nova Prime to come to the rescue, Kitai must slog across 100 kilometers of Edenic but inhospitable Earth and retrieve the other beacon, in the ship's tail section.

Not to worry: Kitai has a Navi Band, a digital hookup wrapped to his forearm that allows Dad to see what he sees: herds of buffalo, flocks of birds, and uh-oh, a congress of killer baboons. It also allows Dad to impart important messages along the lines of "fear is not real" and other samurai-like koans. You half expect the General to say, "feel the Force, Luke," but that would be another movie.

Based on a story by Smith, with a screenplay credited to Shyamalan and Gary Whitta (The Book of Eli - and this one has biblical aspects, too), After Earth is refreshing in that it's not rife with fast-cuts, whooshing camera shots, and overblown visual effects. The Ursa and the baboons, a pack of predatory feline beasts, and a giant condorlike bird are all rendered in expert CGI, seamlessly embedded in the action.

And speaking of action, the elder Smith is anything but a superhero here. Crumpled in his command module, he addresses his kid, or himself. The takes are long and unhurried, and if the words are sometimes ponderous, hey, it's nice to not feel rushed for a change.

Just get that other guy a prosthetic.

After Earth **1/2 (out of four stars)

Directed by M. Night Shyamalan. With Will Smith, Jaden Smith, Zoë Kravitz, and Sophie Okonedo. Distributed by Columbia Pictures.

Running time: 1 hour, 40 mins.

Parent's guide: PG-13 (violence, sci-fi action, adult themes)

Playing at: area theatersEndText