An Americanized remake of the 1998 French film "Le Diner de Cons," "Dinner for Schmucks" features a mean-spirited premise with a logline that could have paved the way for an uproariously cutthroat black comedy one imagines Neil LaBute might have made in the late-1990s/early-2000s before he gave in to the Hollywood system. Lamentably, director Jay Roach (2004's "Meet the Fockers") and screenwriters David Guion and Michael Handelman (2007's "The Ex") can't resist the temptation to go soft and predictable as they strive to make an already uncomfortable plot more palatable for mass audiences. The results are wildly uneven, littered with occasional offbeat laughs and a lot of downtime where the proceedings range from contrived to irritating to kind of creepy.

Tim (Paul Rudd) is an ambitious executive at an investment firm, low on the totem pole but on the verge of receiving an important job promotion. Before this can happen, he must attend a top-secret monthly dinner hosted by boss Lance Fender (Bruce Greenwood) where each guest brings along the biggest idiot they can find. The winner receives a trophy and, because new potential Swiss client Mueller (David Walliams) is going to be in attendance, Tim has extra reason to impress. Inwardly, he is totally against the whole thing—so, too, is artist girlfriend Julie (Stephanie Szostak) when she finds out about it—but then fate drops Barry (Steve Carell) in front of his car and into his life. A lonely IRS employee who spends his free time creating elaborate dioramas with dead mice, Barry becomes so excited by Tim's invite to dinner he shows up at his apartment a full day early and goes on to randomly turn his world upside down.

The opening titles montage of "Dinner for Schmucks" detailing a constructed miniature landscape populated by taxidermied rodents is cutely quirky, an appropriate setup of the Barry character before the viewer has properly met him. It's only later, after being bombarded with dioramas recreating famous paintings and notable moments in history—all starring deceased mice dressed up like Barbie and Ken dolls—that the reality of this hobby sets in and suddenly seems awfully macabre bordering on perverse. Such is the case with Barry himself, a peculiar individual who comes off as a sympathetic sad sack one minute and an infuriating tornado of terror the next. The conception of this character is deeply flawed, a key miscalculation the film never overcomes. Barry must be at least somewhat intelligent if he has a job at the IRS, and yet he is so inept and/or uncouth at social interaction and so clueless about what's going on around him that he seems less like an idiot and more like someone who is genuinely mentally disabled. It's easy to laugh at a dumb person, but not so much if that person has deeper handicaps. Even if that was not the intention of the filmmakers, that is unfortunately how it is received.

If Barry's antics grow tiresome very quickly—there comes a point when you may actually wish for the movie to be over simply so you can get away from him—and Tim's conflicts with his girlfriend, his coworkers, and actions he's not proud of are those predicated on conventions, thank goodness several of the side characters and supporting performers brighten things up. Lucy Punch (2007's "Hot Fuzz") is sinfully funny in the go-for-broke role of Darla, an obsessed, animalistic one-night-stand from years' past who reenters Tim's life wanting to rekindle what she conceived as a flame. A scene where Darla's playful come-on to Barry quickly turns into a vicious vase-throwing fight after a few scrapes is a definite highlight, and so is another set-piece where she shows up unannounced at a lunch Tim is having with clients and orchestrates a marriage proposal by posing as Julie. Darla is truly daft in a comical way, and actually would have made for a far more appropriate guest for Tim to escort to the dinner of the title. Also making the most of their screen time are Jemaine Clements (2009's "Gentlemen Broncos"), sensationally over-the-top as laughably pretentious artist Kieran Vollard, and the scene-stealing Kristen Schaal (2010's "When in Rome") as Tim's tell-it-like-it-is assistant Susana. On the other end of the spectrum, Zach Galifianakis (2009's "The Hangover") is nearly unbearable as Therman, a man who claims to be able to control minds. His every appearance equates to fingernails on a chalkboard.

The climactic "Dinner for Winners," as Tim's coworkers have nicknamed it, should be the picture's centerpiece. With each guest bringing their own "idiot" guest, the outcome should have bridged the gap between rude and hilarious—a so-wrong-it's-right proposition. Instead, director Jay Roach botches it. The people everyone brings are kind of weird, but not humorous, and the employees who are in on the joke remain perfectly nice and respectful to them. Sure, what they are doing behind their backs is cruel, but they aren't actually humiliating the guests of (dis)honor and even provide one of them with a trophy. Nevertheless, one can count the minutes before Tim, struck with a guilty conscience, confesses the truth about the dinner to Barry and things take a serious turn. Following that, of course, is the romantic make-up session where Tim admits to Barry the mistakes he's made in his relationship and Julie walks in behind him, overhearing the confession and falling in love with him all over again. Is that a spoiler? Not when it's as inevitable as the sun rising.

"Dinner for Schmucks" never quite commits to what it wants to be. It's not ruthless enough to go dark and it's not endearing enough to work as feel-good fodder. Tim's ultimate friendship with Barry isn't believable after watching how much he's been driven crazy by him; they become buddies only because the formula demands it. Paul Rudd (2009's "I Love You, Man") continues his straight-guy roles as Tim—it's time to branch out—and Steve Carell (2010's "Date Night") wavers between annoying and kind of mournful as Barry. Carell fulfills what is asked of him, no doubt; it's the writing of the character himself that is at fault. By not picking an angle and sticking with it—the tone is all over the place—"Dinner for Schmucks" ends up being very middle-of-the-road, good for a few chuckles but largely a wasted opportunity.