RUN FATBOY RUN — ** 1/2 — Simon Pegg, Thandie Newton, Hank Azaria; rated PG-13 (vulgarity, profanity, violence, brief partial nudity, slurs, brief drugs)

British comic actor Simon Pegg has impressed in the cult hits "Shaun of the Dead" and "Hot Fuzz." He even stole scenes from Tom Cruise in "Mission: Impossible 3."

But he's been looking awhile for the kind of movie vehicle that will help him cross over to mainstream success. Unfortunately, "Run Fatboy Run" isn't quite it.

While he gets some mileage out of this sketchy material, he's undermined by story and character problems, as well as the limp, uninspired direction of actor-turned-filmmaker David Schwimmer.

Pegg stars as Dennis, an underachieving Brit who's really not so much obese as he is out of shape. However, his paunch didn't stop him from running out on a marriage to Libby (Thandie Newton), who was pregnant with their child.

Years later, he's still haunted by that personal failure. And he's continually wondering how he can get back in Libby's good graces. But he's just recently learned she now has a picture-perfect boyfriend named Whit (Hank Azaria).

Faced with losing the affections of his ex and his young son, Jake (Matthew Fenton), Dennis promises to straighten up — first, by running the same marathon race as Whit. The trouble is the chain-smoking, adolescent-adult can barely run down the block.

Among the problems with this script (which was co-written by Pegg) is that there are some predictable character turns, especially a sudden change in attitude by Azaria's seemingly perfect Whit. It would have been much more interesting if they hadn't chosen to villainize him.

Also, Newton glowers more than she smiles in the film, and frankly, her character doesn't seem like much of a prize.

However, the father-son sequences with Pegg and newcomer Fenton are genuinely appealing. They nearly redeem the selfish, immature and unlikable main character.

Pegg's "Shaun" co-star Dylan Moran does get a few big laughs as Dennis's unrepentant gambler pal.

"Run Fatboy Run" is rated PG-13 for vulgar humor and references (most of it sexual in nature), sexual language (vulgar slang and profanity), comic violence (slapstick pratfalls and some brawling), brief partial male nudity, derogatory slurs and brief drug references (prescriptions). Running time: 100 minutes.

---

E-mail: jeff@desnews.com