A bitter comedy gets lost in 'Chaos'

From left: Ryan Reynolds, Emily Mortimer, and Stuart Townsend straddle the line between romantic comedy and melodrama in "Chaos Theory." (Alan Markfield)

Ryan Reynolds's makeover continues. The onetime snarkmaster of rude college farces like "Van Wilder" and "Waiting. . ." is hitting 30, and his smooth spray-on tan is beginning to look unbecoming - the mark of an ageless oddity like George Hamilton rather than a smartly shallow frat-boy hero.

So the powers that be have been casting the actor as a befuddled daddy-type in romantic comedies like "Definitely, Maybe" and "Chaos Theory," a new film that's actually been sitting on the shelf for well over a year. "Maybe" was watchable and blandly pleasant; "Theory" is a smidgen better than that, if not the cruelly funny farce the movie's best impulses and its own trailer would have you believe.

After a modern-day opening scene, in which Reynolds is wholly unconvincing as a middle-age father of a bride, "Chaos Theory" flashes back two decades and then forward seven or so years, finally settling into its main narrative about married couple Frank (Reynolds) and Susan (British actress Emily Mortimer, making with a convincing American accent). He's an efficiency expert wound tighter than a tick, she's charming and skeptical, and their banter is pretty sharply honed for a modern multiplex comedy.

Him: "I've got to go, it's 18 after."

Her: " 'Eighteen after' is not a time, it's a symptom, like a twitch."

Him: "You used to think it was adorable."

Her: "I used to pound Jagermeister."

Daniel Taplitz's script natters along like this for a bit, introducing the couple's young daughter Jesse (Matreya Fedor), and then it starts to pull Frank's little world apart with glee. Overnight in the city after giving a motivational speech, he allows himself to be reeled in by a seminar groupie - is there such a thing? - played by Sarah Chalke, and follows that up with an emergency assist to a pregnant mother (Jocelyne Loewen) in need.

Such things are meant to be misunderstood by movie wives, but "Chaos Theory" proceeds to twist the wrench further, until the hero's gears are well and truly stripped and the only recourse is to run across the ice naked at a professional hockey game.

At a certain point in Frank's carefully delineated nervous breakdown, he comes to understand that keeping one's life in order is futile. He embraces whim with the zeal of a born-again convert, making lists of anti-social behaviors then choosing one at blissful random. Reynolds deftly blurs the lines between joy and rage; he's a light comedian playing entertainingly with heavier weights than usual.

There are the pieces of a remarkably bitter and clear-eyed comedy here, something I can imagine Elaine May directing Jack Lemmon in a few movie generations back. Taplitz and director Marcos Siega aren't up to that level. "Chaos Theory" keeps jerking in the direction of melodrama, and finally the cart tips over completely.

A subplot involving Stuart Townsend as Frank's best friend, a cad who has long pined for Susan, trods ever deeper into the slough of seriousness. The film also raises the possibility of bad behavior on the part of the wife before dodging the issue in a way calculated to please the movie's audience while sapping the life out of its characters.

Savor the sharp bits, then, and forget about the cluttered ending, which combines comic attempted homicide with young Fedor behaving as no little girl would under the circumstances. "Chaos Theory" is pretend grown-up fare for moviegoers who've been out of college a decade or so and who are just beginning to freak out about getting older. It's genial enough, but it should be called "My First Mid-Life Crisis Movie."

Ty Burr can be reached at tburr@globe.com. For more on movies, go to boston.com/ae/movies/blog.