Diego, Sid, and Manfred are an unlikely trio trying to survive an 'Ice Age.' Ice Age Voices by Ray Romano, John Leguizamo, and Denis Leary. Directed by Chris Wedge. Written by Michael Berg, Michael J. Wilson, and Peter Ackerman. Rated PG.

Two years ago, 20th Century Fox released Titan A.E., an expensive animated sci-fi feature that critics largely dismissed and moviegoers ignored. The flop wound up costing the company tons of money and several corporate bigwigs their jobs. Since then, the new heads of Fox watched DreamWorks and Disney rake in the cash with Shrek and Monsters, Inc., two films that used digital animation to good effect, and evidently decided that Titan A.E. tanked because its hand-drawn animation was passé.

So now we get Ice Age, a movie whose digital animation makes it look every bit as spiffy as last year's Oscar-nominated hits. Often, the ice forms a plain white backdrop for the characters while their conversation takes center stage. (Comic artists have similarly used wintry weather in Peanuts, Calvin and Hobbes, and South Park.) However, the ice takes many shapes in this film, and the animators do dazzling work in presenting them, from an avalanche's great jagged falling chunks to prismatic architectural material for giant underground caverns. The computer-generated animals who serve as characters match the sleekness of the backgrounds; their fur looks realistic, but their angles are all clean and their smooth surfaces are impossibly polished. The saber-toothed tigers practically look like corporate logos. On a purely visual level, this movie doesn't top Shrek or Monsters, Inc., but it's definitely in the same league.

Guess what, though? It doesn't make much difference. Shrek and Monsters, Inc. were popular because their scripts had snappy dialogue and complex characters whose dramatic situations were easy to identify with. The digital animation made the ogres and monsters look real, but those characters felt real to begin with because of how thoroughly they were imagined in the writing stage.

By the same token, Titan A.E. didn't fail because of its visual style, which was actually fairly accomplished. It failed with audiences and critics because its characters were either indecipherable or made out of cardboard, and because some high-powered scriptwriters couldn't inject much humor into the story. The humor situation's somewhat better in Ice Age, but the newer film still has many of the same problems.

The movie's main character is Manfred (voiced by Ray Romano), a woolly mammoth who has steadfastly refused to join the herd of mammals migrating south to escape the oncoming Ice Age. He saves a chattering sloth named Sid (voiced by John Leguizamo) from a couple of rampaging rhinos, and the small, persistently chattering Sid is so grateful that he resists all of the big, grumpy Manfred's attempts to ditch him -- sound familiar? The pair are in full bicker when they find a human baby who has been separated from his tribe by an attack from a pack of saber-toothed tigers. Manfred and Sid want to return the baby to its parents -- again, sound familiar? -- but the only way to find the humans is to rely on the tracking skills of Diego (voiced by Denis Leary), a tiger who may well be planning to eat his traveling companions.

The comic set pieces work pretty well. The animals travel beneath a frozen lake, occasioning a series of wordless sight gags that the movie trusts the audience to catch. There's also a run-in with a pack of hostile dodos who quickly demonstrate why their species became extinct. The recurring appearance of a nontalking squirrel with an acorn is a reliable source of laughs, too.

These scenes contain the movie's best material, and yet none of it is related to the story or the characters we're following. The plotline about returning the baby is soggy enough, but the movie piles on that by giving Manfred his own tragic fatherhood issues, which explain his prickliness. The animators are good at making the mammoth look cranky, but they can't make him look sad. The same goes for Romano's voiceover work, although, somewhat weirdly, the script doesn't have him say anything in response to the big revelation about Manfred's past. Diego's crisis of conscience isn't convincing, either, partly because we don't believe a tiger might go against his predatory instincts and defend the good guys (the same credibility problem ruined Disney's The Lion King), and partly because there's nothing in the script to make us believe that. The supporting cast has vocal talents as diverse as Jack Black, Cedric the Entertainer, and Goran Visnjic, and none of them register. In an animated film, that's a sure sign that the writing isn't there.

Every year, there's at least one animated feature that can stand with the best live-action films. The kids who'll probably turn this movie into a hit may be too young to learn how to apply standards to the films they see and demand more from their entertainment, but this miscalculated movie is a good reason to teach them to do that. Sadly, Ice Age isn't good enough to do anything else for them. And that just isn't cool.

You can reach Kristian Lin at kristian.lin@fwweekly.com.