LOS ANGELES - "Up." The title is deceptively simple, which is fitting, because the latest achievement from Pixar Animation is deeper and more complex on every level than it would initially appear.

It's a classic B-movie exotic adventure, the kind that inspired Steven Spielberg and George Lucas to make "Raiders of the Lost Ark," but it's told through the most high-tech, gorgeous 3D animation.

It's a mismatched buddy comedy, the kind we've seen countless times before, but the buddies are a curmudgeonly 78-year-old man and a tubby eight-year-old boy -- who wind up together in a flying house, travelling to South America.

And, as with many family films that get pumped out each summer, it has talking dogs. But it's how the dogs talk and what they say that are truly inspired, and oddly realistic.

Pete Docter (Pixar's "Monsters, Inc.") and co-director and writer Bob Peterson turn their imagination this time to human beings, rare creatures in the animated kingdom. But between the richness of the characters, the meatiness of their interaction and the authenticity of the details, it won't take you long to forget that "Up" is a cartoon and become immersed.

We begin some 70 years ago, when Carl Fredricksen was just a boy, worshipping the glamorous explorer Charles F. Muntz (voiced by Christopher Plummer). Even then, Carl moved with the quiet cautiousness of an old man -- that is, until he meets the energetic tomboy Ellie, who brings out the fun he never knew he had inside him.

"Up" shares their decades-long romance in a lovely, poignant montage. It lasts just a few minutes without a single word spoken -- just Michael Giacchino's wistful score to accompany the images -- but it tells a full and satisfying story. Don't even bother holding back the tears: They'll come, and deservedly so.

From there, though, there's nowhere to go but up, literally. Now a crusty widower facing eviction and an antiseptic life in a retirement community -- and voiced perfectly by Ed Asner -- the former balloon salesman ties thousands of helium balloons to his house and soars into the clouds. His eventual destination: Paradise Falls in Venezuela, where he and Ellie always promised each other they'd go. (The reflections of the balloons' rainbow hues are wondrous as he floats past streets and buildings.)

But Carl has an unexpected passenger: Russell (endearing newcomer Jordan Nagai), an overeager Junior Wilderness Explorer who had knocked on Carl's door hoping to earn the final badge he needs to become a senior scout: assisting the elderly. They make an unlikely but lovable pair: the rigid Carl (who resembles a latter-day Spencer Tracy with his linear mouth, square-shaped glasses and bushy white hair) and the ebullient Russell. Their bond is sweet, their journey joyous.

Peril lies along the way, too, although "Up" is suitable for the whole family; one of the most striking images is of the small, rickety house drifting toward a wall of ominous thunder clouds. Once they reach Paradise Falls, they find themselves surrounded by a pack of attack dogs. Among them is the lovable Dug (voiced by Peterson), a mutt who's just so darn happy to meet new people, he instantly insists Carl become his master.

Dug, like the other dogs roaming the rain forest, has been outfitted by his mysterious owner with a collar that voices his thoughts. This might be the most ingenious invention ever and Dug's canine ramblings provide the chief source of consistent comedy in "Up." The other is a rare four-metre bird -- whom Russell names Kevin -- who's adorably gawky but is being hunted by the other dogs, who aren't nearly so friendly.

We won't tell you the direction "Up" goes from here. We'll just say it's creative and unexpected, like everything that came before it and the other films in the Pixar canon.

Three and a half stars out of four.