Reese Witherspoon and Vince Vaughn are paired in the holiday romantic comedy Four Christmases. (John P. Johnson/Warner Bros.)

Vince Vaughn is a big, likeable star who plays big, likeable guys. In Swingers, Old School, Dodgeball and the definitive party-boy movie, Wedding Crashers, Vaughn is a fast-talking hedonist, living entirely in the moment, always indulging his baser impulses. Vaughn’s characters refuse to assume adult responsibility. He’s the kind of guy everyone wants to hang out with — the hipster rogue, the life of the party. And that’s why we love him. Earlier this year, Forbes magazine named Vaughn the world’s most profitable movie actor, weighing his salary against ticket totals.

Scuttled by a lazy script and a surprising lack of chemistry between the two leads, Four Christmases never gels.

Reese Witherspoon is also a likeable star with a comedy track record. As Elle Woods in the Legally Blonde movies, she played ditzy, pampered and charming, and proved she could deliver as the lead in a lucrative franchise. Witherspoon contributed a much darker comic hue to Alexander Payne’s indie satire, Election. Her depiction of high-school student politician Tracy Flick as a tightly wound Machiavellian was the perfect counterpoint to Matthew Broderick’s schlubby teacher.

So, on the surface, it seems sensible to cast Vaughn and Witherspoon together in a light, home-for-the-holidays comedy. Add a gaggle of former Oscar winners (Robert Duvall, Sissy Spacek, Jon Voight, Mary Steenburgen) to play their unhinged kinfolk and, well, you can bet that Warner Bros. is counting on Four Christmases to deliver some Meet The Parents-style moolah. That’s the uncomplicated formula, but things don’t really add up. Scuttled by a lazy script and a surprising lack of chemistry between the two leads, Four Christmases never gels.

The set-up is wafer thin: Brad (Vaughn) and Kate (Witherspoon) have been living together for three years, and although they’re doing well financially, they have no desire to marry or have kids, given the wretched experiences they had growing up in broken homes. As Brad wryly notes, “You can’t spell ‘families’ without ‘lies.’”

Each holiday season, in an effort to avoid their horrific clans, they head off to exotic destinations like Fiji, but tell their folks they’re actually going away to do charity work. After getting fogged in at the San Francisco airport, Brad and Kate realize they must spend Dec. 25^th visiting each of their (divorced) mothers and fathers. As the title baldly states, this is the year they must endure not one, but four dysfunctional family Christmases. Unfortunately, this joyless procession also turns into an endurance test for the viewer.

First comes Duvall as Brad’s redneck father, who piles on the emotional abuse while his other two adult sons (played by Jon Favreau and Tim McGraw) dole out physical pain, pounding on their brother at every opportunity. The slap-shtick wears thin very quickly. Steenburgen wrings a few laughs out of her role as Kate’s oversexed mother. Spacek, as Brad’s mom, and Voight, as Kate’s father, are given practically nothing to do. With all the whack-job parents, catty siblings and vomiting nephews and nieces floating around, there are simply too many characters here: none of the relatives gets enough screen time to become anything more than caricatures.

Kate (Reese Witherspoon) tries to get over her childhood fears of the "jump jump" in Four Christmases. (John P. Johnson/Warner Bros.)

Vaughn and Witherspoon aren’t well served by the plodding script, and they seem to inhabit two entirely different universes (and it’s not just the fact that he’s 6’5” and she’s 5’2”). It’s tough to understand why their characters are even attracted to each other. Vaughn is playing his standard man-child. By now, it’s a role he can do in his sleep, and he struggles mightily to get the party started, especially during a scene in which Brad is forced to play Joseph at the last minute in a nativity play. But Vaughn can never really cut loose; Brad is always hemmed in by the killjoy Kate, who rarely enjoys her partner’s bluster.

The lack of chemistry between the two stars is palpable. Witherspoon appears to be far less comfortable than Vaughn at broad physical comedy. One scene in which she battles a group of children in a “jump jump” (a.k.a. “bouncy castle”) falls particularly flat. Stories emanated from the Four Christmases set about “creative differences”; it was reported in many places that Witherspoon’s meticulous methodology clashed with Vaughn’s shambling, improvisational style. Whatever the on-set reality was, the two don’t connect comedically on screen.

Vaughn is simply funnier when he’s hanging out with the guys, and being encouraged to pursue those hedonistic impulses; let him riff off a chilled-out Owen or Luke Wilson and he’ll usually produce comedy magic. If he’s being chided by Witherspoon or Jennifer Aniston (see: The Breakup) — not so much.

Four Christmases limps predictably to a sentimental conclusion about the importance of family — a completely insincere finish, given the psychological horrors that unfold in the preceding 90 minutes. Here’s hoping your holidays are more pleasant and heartfelt than this hollow effort.

Four Christmases opens on Nov. 26.

Greig Dymond writes about the arts for CBCNews.ca.