Life isn't easy for the Croods, the cave-dwelling Neanderthal family in DreamWorks Animation's latest offering, The Croods, a visually dazzling, if empty-headed, 3-D family action-adventure powered by some serious computer-generated animation and A-list voice actors.

The Croods are a tight-knit family of six headed by patriarch Grug Crood (Nicolas Cage) and his wife Ugga (Catherine Keener), who live in a cave in a vast, barren landscape populated by the odd bird, tiger, lemur, or dino. Odd indeed: Codirectors Kirk DeMicco (Space Chimps) and Chris Sanders (How to Train Your Dragon) don't even pretend at realism, filling their movie instead with brightly colored fantastical flora and fauna.

Grug isn't the sharpest tool in the shed but he's fiercely loyal and protects his family with all his might, imposing on them a strict routine - wake up, hunt for food, rush back to the cave before sundown. The world is a dangerous place, Grug keeps telling his kids.

"Fear is good; change is bad" is the Crood family mantra.

Not so for Grug's eldest child, teenage rebel Eep (Emma Stone), who breaks all the rules, including the most dread command of all: Don't ever leave the cave at night. She does, and one night she runs into the first non-Crood boy she's ever met, a dashing guy named Guy (Ryan Reynolds), who wanders around in the dark carrying with him a most wondrous thing called fire.

Guy is way evolved: He has fire, he can make tools, and he has befriended animals, including a long-tailed furry pet named Belt (Chris Sanders), who wraps around his waist and holds up his pants.

Guy persuades the Croods to leave cave life behind, leading them west through many crazy adventures. Guy teaches them how to use tools, how to swim, how to cook. And most of all, how to enjoy themselves!

After many moons, Guy brings them to a place called Tomorrow. A lovely place.

The Croods offers very little for grown-ups: It has none of the clever, subversive wit, wordplay, or imagery that made DreamWorks' Shrek series so appealing to parents and kids alike. (It's hard to believe the story was conceived by Monty Python alumnus John Cleese.)

For all that, the movie is well-edited and lean, a fast-paced, action-filled bit of froth that manages to be diverting and surprisingly fun.