I was about to describe the Jason Bateman/Melissa McCarthy vehicle “Identity Thief” as a dismal new comedy, but that’s not accurate. There is not a premise, character, situation or theme in this crass film that is in any way new. At best it’s perversely interesting as a major misstep for both stars.

He’s Sandy Patterson, a Denver corporate accountant, and she’s Diana, a free-spending Florida scam artist who steals his personal information and trashes his credit rating overnight.

With his reputation and job dangling by a thread, he heads cross-country to confront her. With not one but three vengeful pursuers closing in on her, she has little choice but to buddy up with her buttoned-down victim. Hilarity does not for an instant ensue.

You can see why they hoped it would. McCarthy got a deserved Oscar nomination for her energetic work in “Bridesmaids,” and Bateman is a wily underplayer. In a better production their contradictory comic styles might strike sparks. Here they nullify each other. Playing a contrived concept rather than a character, McCarthy is all huge flailing gestures and silly, mugging faces. Bateman phones it in, lobbing an occasional incredulous reaction shot as his co-star lies, cons, seduces and hoodwinks every chump who crosses her path.

As downtrodden nice guy Sandy faces off against harmless-looking but wily Diana, each learns Important Life Lessons from the other. Stand up for yourself! But be nice, too! After about 80 minutes of strenuous huffing and puffing, we shift gears to pathos as McCarthy shows the clown’s sensitive side. The cause of her grudge against humanity is all too blandly sentimental for its own good.

The script by Craig Mazin (of the “Hangover” and “Scary Movie” series) is a tortured exercise in high-concept hokum, one set piece barely linked to the next.

Director Seth Gordon (“Horrible Bosses”) compounds the implausibility, spelling out every plot point as if the movie were an episde of “Sesame Street.”

Suck the surprise, subtext and nuance out of comedy and all you’ve got left is slapstick. Not that even physical humor is well served here. The film uses McCarthy and Bateman as Three Stooges-type punching bags. She throat-chops him. He prangs her in the face with a guitar. I imagine they were each thinking of their agents for motivation.