When Renee Zellweger flashes that sweet smile, bunches her body up in a “right-o, old chap” shoulder shrug and waddle-walks in anaconda-tight dresses, it’s impossible to not root for her.

It’s what earned her an Oscar nomination for Bridget Jones’s Diary, a fresh and fun film revelation even for those with only vague knowledge it was based on a book. Bridget felt like a real woman, trapped in a bizarre love triangle and in the middle of a civilized spat between her parents.

What a shame that, with the shining exception of Zellweger, Bridget Jones: The Edge of Reason feels like a film that has assembled its cast only for the continuity of facial recognition and nothing so important as story, characters or emotion. (Jim Broadbent and Gemma Jones return as Bridget’s parents, reduced to a sorry sight gag through their lavender-colored second wedding.)

Even Hugh Grant’s reprisal of the sexually villainous cad Daniel Cleaver is disaffected and without bite. There’s no real slippery danger to his repeat seduction of Bridget this time, as there was in the original.

How she even ends up near his arms is a silly plot point if ever there was one, coming at a time of uncertainty in her fledgling relationship with lawyer Mark Darcy (Colin Firth, barely skating by here with his masterfully locked-in prissiness).

Concerned Mark’s falling for a leggy brunette colleague (Jacinda Barrett), Bridget flips out (with an accusation of infidelity), walks out (into the arms of Daniel, now Bridget’s TV colleague) and gets shipped out (to a Thailand prison on bogus drug charges).

Zellweger is still perfect in the role, her glaring wardrobe and more subtle physical touches drawing more laughs than the broad slapstick stumbles. (Although her treacherous trek down a ski lift delivers one of the film’s funniest laughs.)

Bridget still is absurd, but identifiable, even for the males in the crowd. Stammering stupidly on the phone as she does to Darcy after an ill-timed hurtful remark is not a sex-specific situation, nor is the tense, cutting talk they share regarding a possible pregnancy.

But if you or I got thrown into a Thai prison on bogus drug charges, we likely wouldn’t lead our cellmates in a slumber-party rendition of “Like A Virgin.” A gimmicky plot diversion leading to Thailand’s sunny beaches is fine for a frothy, fluffy comedy, but not necessarily its dim, dingy jails. Injecting Legally Blonde humor into a Midnight Express setting stops the movie cold.

Even if that idea’s bad, it’s original, unlike strange movie spoofs (The Sound of Music, 10) and rehashed routines. Bridget unintentionally flashes her bum to TV screens across Britain again. Mark wears a horrid sweater at a turkey curry buffet again. The only recycled bit that works is the ninny fight between Daniel and Mark, and that’s only because you rarely see the sort of real-life futile flailing in film fights.

Because of Zellweger’s fine work, it’s not an unwelcome prospect if Bridget Jones evolves as a chick-flick franchise equivalent of James Bond, as she bumbles through the stages of her life. Future filmmakers just have to understand what shook and stirred us about her in the first place.