Although her husband, Phil (JOHN C. REILLY), has a job, he spends most of his free time hanging out with his painting partner, Bubba (TIM BLAKE NELSON), getting high and wondering why he and Justine haven't had a baby yet.

Tired of the way things have turned out and store security guard Corny (MIKE WHITE) trying to get her to attend Bible study classes, Justine takes an interest in Holden Worther (JAKE GYLLENHAAL), a 22-year-old who's just started working at Retail Rodeo with her.

An aspiring writer, Holden still lives with his emotionally distant parents, but becomes instantly smitten with Justine, which also holds true for her as both believe they've found a kindred spirit in the other. The two soon become lovers, with Justine trying to keep that secret from Phil who's suddenly decided to clean up his act and become a better husband.

As the affair continues, Justine's guilt increases and she begins to feel suffocated under Holden's growing obsession with her, all of which leads to some unexpected developments for everyone involved.

Just ask Leonard Nimoy or Max Baer. While the former eventually resigned himself to playing Mr. Spock in six "Star Trek" movies that eventually followed the TV series, the latter never managed to shake his Jethro "Beverly Hillbillies" Bodine persona in either the public or industry's eyes.

It's too early to tell whether the same fate awaits some of today's TV stars, but the longer they appear as the same character in the same show - particularly when they're comedies - the more in danger they appear to be.

Perhaps sensing that, the cast members of TV's long-running sitcom "Friends" rather quickly tried their hands at crossing over to movies, with varied degrees of success and failure. The latest to do so, however, has delivered a strong enough performance in her latest film that it doesn't seem likely that she'll need to be worrying about "Friends the Movie Part IV" just yet.

I'm referring to Jennifer Aniston in "The Good Girl." A small drama that isn't likely to appear on the radar screens of mainstream America, it tells a tale that examines the old "grass is greener" sort of story in something of a quirky drama and black comedy mix.

Considering that it comes from the hands and minds of director Miguel Arteta ("Star Maps," various episodes of various TV shows) and screenwriter Mike White ("Orange County," "Dead Man on Campus") who last collaborated on the equally quirky drama, "Chuck & Buck," that really shouldn't come as much of a surprise.

The comedy angle is a nice addition (with most of it occurring in the discount store or involving its employees), although that's not meant to imply that the film is hilarious. Rather, the humor is droll and often dark in nature. The humor is welcomed, though, because we've seen this sort of story countless times before where an unhappily married person tries to find happiness and vitality through a much younger lover. Of course, this time around, the philanderer is the wife and Aniston does a terrific job playing her.

Gone is the Rachel persona and pretty girl looks whose hairstyle got its own name and inspired copycat fashions. In its place is a woman whose life, job and marriage have turned out to be anything but what she dreamed or imagined for herself. While the dialogue that comes from her mouth occasionally sounds a bit too sophisticated for the role, Aniston makes her a believable character.

The filmmakers also do a decent job in setting up her character and situation so that we understand her unhappiness and reason why she has the affair. That development - exacerbated by her deadbeat, stoner husband getting his act together - obviously conflicts with our initial desire to sympathize with her and her plight. It's a testament to Aniston's performance and the filmmakers' efforts that the character manages to eke her way across the finish line on a slightly positive note (which, no doubt, the comedic elements help pull off by diluting the unsavory material).

As her less than perfect husband, John C. Reilly ("The Anniversary Party," "The Perfect Storm") is also quite good and likewise creates a completely credible character and the one with which the audience - surprisingly - will most likely ultimately sympathize.

Tim Blake Nelson ("Minority Report," "O Brother, Where Art Thou?") appropriately plays his hick buddy with his own deep dark obsession part to a T, Zooey Deschanel ("The New Guy," "Big Trouble") is funny as a retail clerk with a bad attitude and a penchant for radical make-up jobs for customers, while Jake Gyllenhaal ("Bubble Boy," "October Sky") decently plays the obsessed young lover (although this marks the second film in a row - after "Lovely & Amazing" -- in which he's played the same sort of disturbed boy-toy character).

Coming off as something of a combination of "Clerks," "Fatal Attraction" and this year's "Unfaithful" - or at least various elements thereof - the film doesn't always take itself seriously, which is a good thing. The mix of straight drama and black comedy, however, doesn't always result in a perfectly balanced effort, particularly in regards to the film's dramatic momentum.

Yet, for the most part - and especially thanks to Aniston's performance -- it works more than adequately even if the ending isn't exactly what one would call happy. It's also difficult to tell exactly what sort of message the filmmakers are trying to impart about the protagonist, her life and the effects of her choices. Not perfect, but certainly intriguing, "The Good Girl" rates as a 6.5 out of 10.