If you rate comedies by how many times you laugh out loud, Identity Thief isn't a very good movie. Don't get me wrong—it's got a couple of moments where you'd have to be dead not to burst out with a little surprised laughter, spread sparsely around its too-long runtime. But it's just not as funny as it should be, and that's a cardinal sin for an off-season raunch-com. And it's not especially well-written, either. A schlubby guy named Sandy Patterson (Jason Bateman, amusing but going back to the schlubby straight man comedy well one time too many) has his identity stolen by a Florida woman named Diana (Melissa McCarthy). Because local law enforcement is mostly powerless when it comes to identity theft—something to which many of us can personally attest—Patterson heads to Florida himself to capture Diana and bring her to justice. A road trip packed with forced comedy bits and occasional bursts of gory action (the pair is pursued by a sleazy bounty hunter played by Robert Patrick and a couple of ruthless hitmen) ensues.

But Identity Thief has one glorious thing going for it, and that glorious thing is named Melissa McCarthy. If you were left wondering after her star turn in Bridesmaids whether McCarthy was a one-trick pony, Identity Thief is your proof that she's star material. There was one scene very early in the film, just before the first puke joke, where it occurred to me that something weird was happening on screen. And then I realized: "My God," I thought to myself, "She's actually acting!" McCarthy takes a scene that would in a thousand other actors' hands be a standard excuse to ham it up—Diana spends a disgusting amount of Sandy's money at a bar—and supplies it with equal veins of nuance and broad physical comedy. Her Diana is a manic clown, all right—she falls over and dishes out funny neck punches and looks silly when she runs—but McCarthy fills her giant eyes with this desperate neediness that makes all the humor she finds in her character feel a little bit dangerous. You get the sense right away that this is a woman who has no friends and is willing to spend disgusting amounts of money so she can pretend that anyone gives a shit about her.

If McCarthy keeps up with the quality performances, she could be one of the great comedic actors. Anybody can play a loser and make us laugh by acting all antic. But McCarthy takes the very quality that makes Diana funny—her hollowed out center and her desperate need to fill that hole—and also makes that same quality into her tragedy. Let's put it this way: In the obligatory scenes, late in the movie, where Diana's character spills her guts and explains why she's been such a turd for all this time, McCarthy totally got me. She actually made me choke up over a flat character in a tepid comedy. So I can't exactly recommend Identity Thief, because it's mostly a waste of your time. But if you're especially interested in comedy performances and if you like great acting that has been smuggled into otherwise unremarkable movies, you'll find something to enjoy about it.