"Identity Thief" is neither as good as one hopes nor as gut-bustingly funny as one wishes it were, but for all of its extraneous subplots and contrived scripting it's got one decidedly potent weapon in the form of the fearless dynamo Melissa McCarthy (2012's "This Is 40"). Not just some run-of-the-mill "funny girl," McCarthy has been around for well over a decade—"It's a sort of rave thing!" she exclaimed in a memorable scene from 1999's "Go"—working tirelessly as a character actor who can slide so easily between comedy and drama it's difficult to notice the change happening at all. Now that her star has risen, first with her Oscar-nominated turn in 2011's "Bridesmaids" and then with her hit CBS sitcom "Mike & Molly," McCarthy finally has her pick of projects and the cache to earn lead roles in studio pictures—all while shirking the unrealistic fad of being a size 0 in Hollywood. "Identity Thief" is her first headlining feature out of the gate, and while she is consistently better than the material she has to work with, her depth and talent ensures that she elevate everything around her. It takes a special gift to be funny one moment and then cause the viewer's heart to ache the next. John Candy had it, Kristen Wiig has it, and so, too, does Melissa McCarthy.

Sandy Bigelow Patterson (Jason Bateman) is an underappreciated accounts processor living paycheck to paycheck with pregnant wife Trish (Amanda Peet) and their two little girls. His fortune suddenly looks up when he is hired as Vice President at an upstart firm, but within virtually the same breath it all potentially comes crashing down when he finds out there is a woman living it up in Winter Park, Florida, with his identity and credit cards, racking up a debt in the hundred thousands. Because Sandy lives in Denver and the culprit is out of state, he is informed by Detective Reilly (Morris Chestnut) that all of the legal red tape will likely prevent him from being cleared in the scam for six months to a year. With his cushy new job in jeopardy, Sandy decides to travel to Florida, locate the fake Sandy—colorful, compulsively buying and lying Diana (Melissa McCarthy)—and convince her to come back with him to face the music. Diana is not going down without a fight or three, yet she has little choice but to team up with Sandy when she is pursued by both a wild, debt-collecting bounty hunter (Robert Patrick) and two assassins (Genesis Rodriguez, Tip 'T.I.' Harris).

A hybrid of action-comedy and road movie, "Identity Thief" is directed by Seth Gordon (2011's "Horrible Bosses") and written by Craig Mazin (2011's "The Hangover Part II"), no doubt helped along by the improv skills of co-stars Jason Bateman (2011's "The Change-Up") and Melissa McCarthy. The film is overplotted and too long—the villainous characters played by Robert Patrick (2012's "Trouble with the Curve"), Genesis Rodriguez (2013's "The Last Stand") and Tip 'T.I.' Harris (2007's "American Gangster") could have been whited-out of the script and shaved a solid twenty minutes off the 111-minute running time—the rooting interest lying strictly in the prickly relationship between Sandy and Diana and the question of what will happen when the two of them reach their destination in Colorado. Diana is a squirrely sort, her home like "a hoarder's paradise," her instantaneous ability to deceive unparalleled. What she's done to Sandy's life is nothing short of "diabolical," a word he accurately, if humorously, uses to describe her. Nevertheless, she isn't an awful person underneath, the bad decisions she's made in her life deriving from the tough circumstances of her past and the loneliness she's had to live with all her life. Sandy sees this in Diana little by little and, though he is slow to admit it, an unconventional friendship forms between them. Diana is savvy enough to know, however, that he wouldn't care about getting to know her if it weren't for the crime that has led him to her.

Jason Bateman is forever affable as Sandy Bigelow Patterson, acting on the side of an audience asked to ponder what they would do if faced with identity theft (if, that is, they haven't gone through it themselves already). It's a timely and potent topic, and Craig Mazin does well in exposing the flaws of the criminal system when it comes to this subject in the script. Mazin is clumsier in his overall storytelling, from shoehorning in Sandy's first and last name into dialogue to spell out the premise at the onset, to the literally overnight creation of the sleek, furnished new firm Sandy joins, to subplots involving a bounty hunter and assassins that bide time but go nowhere. When it comes to this latter hindrance, Mazin and director Seth Gordon should have figured out how extraneous these one-note supporting characters were and trusted the chemistry of his leads.

If Bateman is just right for his part, credit the actor all the more for suggesting that his initially male counterpart be rewritten as a woman—and expressly for Melissa McCarthy. This male-female dynamic is far more appealing, a twisting of the conventional buddy comedy without feeling the need to introduce a romance into the equation (Sandy is happily married as is). McCarthy is on fire, playing a complicated character that thankfully isn't just a repeat of her "Bridesmaids" role. A scene where she and Sandy stop at a restaurant for dinner and Diana twists his need for her to get something small to stay on budget with that of an overbearing husband criticizing her weight is a comedic standout (Ellie Kemper, also of "Bridesmaids," cameos as the sympathetic waitress). McCarthy and Bateman additionally dig into their drop-down fight set-pieces with the relish of performers unafraid to get bruised and battered for their art, while several serious moments sprinkled throughout that give insight and gravity to Diana's guilt and inner conflicts are beautifully handled by McCarthy. Even if it's all around her, there isn't a shred of artifice in what she does.

"Identity Thief" grows darker as it goes to the point where one must ask how this particular story is going to possibly wrap up while maintaining an upbeat tone to send viewers out on. On their voyage to make it back to Denver and elude capture, Sandy chooses to make one key decision that places him lawfully on an even playing field with Diana. While his victim in this matter is deserving of payback, it still arguably oversteps a boundary that places him in a grey area of morality. This observation notwithstanding, the film finds a happy medium of staying true to its plot and the consequences of the characters' actions while keeping positive and hopeful toward their futures. Frequently amusing but rarely outright hilarious, filled with heart to offset its acidic nature, "Identity Thief" will likely please a target audience who have come to be entertained for two hours. It cannot hope to come close to matching its forefather, 1987's "Planes, Trains and Automobiles," but, then, few movies can.