Empty-nest syndrome and grown-ups returning to live with their parents get a kid-sized allegory in this beautifully animated and funny, if formulaic, odd-couple comedy starring a not-so-grizzled grizzly and a mule-headed mule deer. Open Season, Sony Pictures Animation's second release after Monster House, is impeccably rendered in CGI that ironically approaches hand-drawn imagery. Some of the hardest things to computer-animate are individual wisps moving collectively, like blades of grass, fields of wheat, human hair or animal fur. Yet in a scene of wind stroking a sleeping animal, we see two kinds of fur moving naturally, and then later we see the same fur wet—and looking wet, not sort-of-wet and kind-of-glossy. Directors Roger Allers and Jill Culton and their team give their characters impressive weight and texture. Even in the close-up scrutiny afforded by 3D IMAX, the animation holds true.

So do the story and the humor, which follow the buddy-movie thing with great grace if nothing groundbreaking. Set in some Rocky/Yukon somewhere, the movie begins with forest ranger Beth (voice of Debra Messing, with surprising parental heart and no shtick), who hosts a national-park stage show with Boog (Martin Lawrence), a big bear she'd rescued as a cub and raised. Boog (shades of the legendarily bear-like Baltimore Orioles first baseman Boog Powell) loves his little unicycle, his home in Beth's garage, and Beth, but there's something stunted in the fact that he's fully grown but still sleeps with a teddy bear.

The locals seem more-or-less amused by the bear lady, though the wise and kindly Sheriff Gordy (the wonderful Gordon Tootoosis, every word soothing and right) tells Beth that the longer she keeps Boog, the harder it will be for him to eventually adapt to the wild. Then there's the local crazy-woodsman hunter, Shaw (Gary Sinise), who plays air guitar on his rifle, Lorraine, and skirts the law to bag his prey. Like the deer he "just happened" to hit with his pickup.

The hood-mounted deer, Elliot (Ashton Kutcher), isn't quite dead yet, though he's missing an antler, and with Boog's casual assistance goes free. Though humans can't hear the animals speak, Shaw, seeing this, senses there's more communication going on than seems natural, fueling an apocalyptic paranoia that's the film's most original bit. It's about time animated people began to notice these things.

The annoying Elliot tempts Boog from his pet-like haven with the devil-lure of chocolate. The two bust into a convenience store and go all Animal House, followed by Boog's candy-hangover and a terrifically choreographed misunderstanding that gets him and Elliot dart-gunned and choppered to the far woods. There, the two unnatural animals have to survive. Bad enough Boog can't even fish; Elliot, it turns out, is the cast-off runt of the herd—and called "Smelliot" by the full-of-himself buck Ian (Patrick Warburton, who by law should appear in every animated feature).

With two particularly good set-pieces—one involving a flood, the other a wonderfully nasty slapstick version of “When Animals Attack”—and a little bit of booger and bathroom humor (hey, doesn't a bear you-know-what in the woods?), this is a kid-flick, no doubt. But there's affecting emotion with Beth at the end, and Lawrence and Kutcher, however and whenever they recorded, have chemistry.