Up carries on that tradition, and if it fails to resonate with the same emotional force as last year’s WALL*E, it is just as ambitious, tracing the life of its resilient hero, Carl Fredricksen, from childhood well into his senior years. Most of the film finds Carl (voiced by Ed Asner), still youthfully vigorous as a grumpy old man, determined to honor the legacy of his late, beloved wife even as urban development threatens to swallow their cozy home. Yet co-directors Pete Docter (Monsters, Inc.) and Bob Peterson give us his backstory too, in the form of a poignant four-minute montage that sums up a lifetime of memories.

It’s a brilliant sequence, wordlessly recounting the magical romance between Carl and Ellie that begins as a chance encounter between two wannabe adventurers bound by their mutual love of Charles Muntz, a daring explorer whose feats are chronicled in newsreels. Ellie dreams of building a home atop the cliffs of Paradise Falls, the South American hideout where Muntz’s enormous airship is said to be docked. It is a dream ultimately deferred, but she and Carl find simpler pleasures in each other’s company.

Widowed and alone for the first time in decades, Carl at 78 is not so much helpless as without purpose. That changes when push comes to shove: Faced with eviction, he straps thousands of helium balloons to his home and takes flight, bound for Paradise Falls and the fulfillment of a lifelong ambition.

There are surprises along the way, the biggest coming in the form of Russell (Jordan Nagai), a pint-sized stowaway and full-time Boy Scout bent on getting his merit badge for assisting the elderly. He earns it the hard way, helping Carl drag his hovering home through the South American jungle in a fashion that pays subtle tribute to Werner Herzog’s Fitzcarraldo. Their travels are often played for laughs – Carl is rarely wanting for a curmudgeonly aside – but the dramatic stakes get raised a notch when the odd couple stumbles onto Muntz’s legendary refuge.

Muntz (Christopher Plummer) is every bit the eccentric one might expect – he lives in his airship with a small army of dogs whose collars translate guttural barks into English – and far more ornery. When Carl and Russell interfere with his pursuit of an exotic bird, Muntz reveals his inner Kurtz, turning on his guests with deadly resolve.

If Up sounds a shade darker than previous Pixar offerings, there’s a reason. Docter and Peterson know better than to pander to the children in their audience, so it comes as little surprise that they handle themes like aging and death so matter-of-factly. The world they have created here is vibrant and exquisitely detailed, a worthy choice for the studio’s first 3-D adventure, but the movie’s underlying humanity trumps even its splendid technical achievements.

Does Up belong in the pantheon alongside Pixar’s strongest efforts? Not quite. As a feat of the imagination, it is on a par with the studio’s finest – among them, Toy Story 2, The Incredibles and my personal favorite, WALL*E – but Up occasionally loses focus, moving in too many directions at once to concentrate on Carl and Russell’s burgeoning friendship.

It’s a minor complaint, really, but also worth noting. Up is clever and handsome, but only sporadically as moving as the best of its cinematic forebears. To be fair, Pixar has set the bar impossibly high. That they clear it here by a foot and not by a mile doesn’t mean they haven’t succeeded in serving up extraordinary entertainment.