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The country needs a lot of things right now, but another Planes, Trains, and Automobiles rewrite is not among them. The formula claims among its victims Robert Downey, Jr. and Zach Galifianakis, both hung out to dry in 2010’s Due Date. So it’s just shy of a miracle that director Seth Gordon (Horrible Bosses) achieves success with Identity Thief, a strange-bedfellows slapstick romp with an emphasis on the slap. It is, in fact, a brutal film, even more than the trailer would have you think. It asks us to laugh at total debasement, at the fat and illiterate, and at horrible acts of violence. Yet laugh we do, thanks to a keen comic balance between Jason Bateman and Melissa McCarthy, two actors who share a remarkable (and, yes, very much against-type) chemistry.

In the film, they also share a name: Sandy Bigelow Patterson, Bateman’s real name that Diana (McCarthy) steals along with his social security and credit card numbers. The real Sandy is VP at a Colorado startup whose corporate affairs are in parlous shape. By night, he’s the standup father of two darling daughters and husband to Trish (Amanda Peet, in a minor but welcome turn). Diana, meanwhile, is a gleeful identity thief (hey!), a sort of Ignatius C. Reilly-as-pathological liar with a serious home-shopping habit. She’s also into some deep shit with an unnamed foreign organized crime syndicate (they seem to be Central American in the main, but the film is somewhat hazy on this point). Soon, straight-man Sandy finds his credit, job, and freedom imperiled, so he flies to Florida to hunt down the woman who stole his life.

The hilarity that follows is a picaresque nightmare, like a Discovery Zone for sadomasochists. Sandy clocks Diana with a toaster, a guitar, and other various implements; Diana, a tougher cookie altogether, prefers the efficiency of the throat-punch/crotch-kick combo. Cars are bought, borrowed, or stolen and then demolished with equal promptitude. Once he stops getting scammed or throat-punched by Diana, Sandy begins to take her lead, loosen up and, you know, just go with the flow. (See: Martin, Steve, 1987.) But a gnarled, muscled bounty-hunter is suddenly close on their heels, with those submachine gun-toting criminals not far behind, and the race from Florida to Colorado pauses only twice. Once is in Georgia, where Diana seduces a barfly named Big Chuck (Modern Family’s Eric Stonestreet) and proceeds to have raucous, bed-breaking sex with him while Sandy plugs his ears in the bathroom. The second stop is in St. Louis, where Sandy takes a page out of Diana’s dirty playbook and scams a credit card from his own company. This Horrible Bosses-style moment of sticking it to the man is an important one for the character. Bateman plays Sandy with more of an edge in his voice, and a shorter temper in general, than his usual overwhelmed good guy, and his Sandy shows a certain bitter fearlessness in this chapter. (It’s also possible that after playing the straight man for so long, Bateman himself is beginning to feel as put-upon as his characters.)

After a few tangles with the authorities and some conveniently dispensed-with villains, we find ourselves in Colorado, and nuts if everyone hasn’t learned something along the way. But was it funny? And was it right to laugh? Few may trouble themselves over the latter question, but the answer to both is a resounding yes. McCarthy and Bateman don’t just feed off each other; they devour each other in fast-paced, enclosed-area scenes that bristle with uncomfortable hilarity. Screenwriter Craig Mazin, who cut his teeth on the Scary Movie franchise, was fortunate in this opportunity to lean on two improvisational whizzes for some of the film’s best moments. McCarthy’s physical comedy deserves a panegyric of its own, but the actress who fell off a cruise ship in Bridesmaids—-” pinballed down, hit a lot of railings, broke a lot of shit,” as her character puts it—-goes full-on WWF here. She is clocked and pummeled. She dispenses surgical violence not out of fury but out of convenience. After a Dodge Charger slams into her, she shakes it off, explaining to Sandy in businesslike fashion: “You just gotta loosen your legs.” Putting a plus-sized actress through the ringer like that would normally smack of the exploitative, but McCarthy is in full control here. (One imagines that when they proposed a Charger, she suggested an El Dorado.) Not a selfish actor, she nonetheless steals each scene—laughing, like her character, all the way to the bank.