Susan and Melissa’s comic road trip to self-discovery

From nowhere she came to steal one of the biggest movies of 2011. Then she did it again with a bigger star and a buddy movie that played to all her strengths and a global audience’s expectations.

Those movies were Bridesmaids and The Heat. The stand-up comic turned scene-stealer was Melissa McCarthy. In Bridemaids she was the sweaty fat one. In The Heat she was the slobbish, foul-mouthed Boston cop in partnership with Sandra Bullock. Now she co-produces and plays the title role in Tammy, the tale of a small-town girl stuck in a rut who hits the road when her partner does the dirty on her. What’s more, she takes her slutty, boozed-up grandmother along for the ride.

The ensemble cast reflects her popularity and ability to attract audiences. The line-up includes Kathy Bates, Toni Collette, Sandra Oh, Dan Aykroyd, Gary Cole, Alison Janney, Mark Duplass and, as the promiscuous, alcoholic granny, Susan Sarandon. McCarthy co-wrote the script with her husband, Ben Falcone, who is also the film’s director. It was something of a labour of love for them both.

“Ben and I both grew up in Illinois,” says McCarthy, “and that’s kind of why when we started writing it, Ben said this woman is from where he grew up. And that’s also where I went to college. So, we had to base it on real people we know and what it’s like when you feel stuck. I think there are people that really love the comfort of their small town and there are people that feel stuck by it. That was our jumping off place: if you’re really stuck in this rut and in this whole little tiny world of things you don’t like, how hard do you have to get hit to bump you out of your vicious cycle? So, we hit it pretty hard.” The blue-collar, profanity-spitting, wild-haired, rosy-cheeked tubby trier is a trademark and brand that 44-year-old McCarthy has made her own.

Yet for her own pet project she and Falcone opted for characters that sit outside of the standardised Hollywood formula. Falcone denies ever attempting to make a subversive movie. Instead he and the missus opted for realism – and funny actors.

“We worked on the script for a long time before we actually got the chance to show it to people and make the movie,” recalls McCarthy. “And by the time we were ready to show people, we’d had it for years and we knew these people and I felt protective of them.

“So, I think, if somebody wanted a bigger scene or a bigger trailer moment, we just knew if that character would do that or not; it doesn’t have to be bigger or flashier. It just has to stay in the right realm of the story. For me, if you can walk that line of more eccentric characters, you can push pretty far. But if you stay on the side of reality, I think it’s always funnier.”

Was she nervous of having such big guns – like Kathy Bates – read her script? McCarthy laughs. “I was literally coming apart at the seams. I was like, ‘I don’t know if she’s ever going to read it but the fact that it’s in her house is making me have weird breakdowns all throughout the day.’ It’s still dreamy to me.”

Stateside critics have been lukewarm to Tammy, calling it a misstep and a misfire. Maybe it’s an experiment for McCarthy and Falcone – a movie that takes her established persona and gives it a twist. “One of the things I loved about the character, Tammy, is that kind of confidence, right or wrong, in her world. I’ve always loved playing that.”

• Tammy (15) is on saturation release.