Melissa McCarthy has earned her moment, and it is now. After scaring

Melissa McCarthy has earned her moment, and it is now. After scaring up an Oscar nomination for Bridesmaids and dragging The Heat and Identity Thief into the box-office winner’s circle, McCarthy gets to generate her own projects. So here’s Tammy, an unabashed vehicle for her specific strengths: She wrote it with her husband, Ben Falcone (the talented comic actor who played the air marshal in Bridesmaids), and he directed. The movie gets a mixed grade, because it doesn’t answer the central question about her talent: Can McCarthy go beyond antic co-starring roles and carry a movie as the sole lead?

Tammy is an unhappy fast-food worker who gets fired the same day she discovers her husband with another woman. This prompts a road trip with her man-hungry, alcoholic grandmother, played with spirit if not much credibility by Susan Sarandon. Grandma hooks up with a swinger (Gary Cole, too little used) whose son (indie stalwart Mark Duplass) is set up as a possible escort for Tammy. This is where the movie gets tricky: We’ve met Tammy as an uncouth, foul-mouthed dope, but now we’re expected to play along as emotional realities are introduced into what had been a zany R-rated comedy. That kind of shift can be executed, but McCarthy and Falcone haven’t figured out the formula yet.

Tammy does perk to life when McCarthy gets to play her signature scenes: charged situations featuring odd people, with enough space for her non sequiturs and improvisations. The early scene in which she’s fired is a dandy—Falcone plays her boss, a man whose heavy perspiration Tammy labels “medical.” She later robs a fast-food outlet, in an extended and funny scene played with a bag over her head. (You know a performer has defined her comic persona when she scores big laughs with her face covered.)

Occasionally McCarthy manages to make even a raunchy one-liner ring true, as when she aggressively and prematurely kisses Duplass and he backs her off: “I don’t want your tongue down my throat.” Her reply—“Where do you want it?”—is offered lewdly but also with a weird kind of innocence that catches something truly sad about the character. Of course the problem is that Tammy’s so extreme she’d be unbearably pathetic if taken straight. The movie can’t handle that, so—while McCarthy remains an interesting test case for defining a leading lady in Hollywood—this one’s a misfire.Opens Wed., July 2 at Sundance and other theaters. Rated R. 96 minutes.

film@seattleweekly.com