Emma Stone - Spiderman's new squeeze shows her mettle in the Deep South

Emma Stone stars in this year's sleeper smash, race drama The Help, and is soon to cosy up to Peter Parker. James Mottram meets the actress

For a girl who trades on easy-going charm, Emma Stone's inexorable rise over the past year seems to be the result of precision plotting. This is the actress who, aged 15, gave her parents a PowerPoint presentation entitled Project Hollywood, to convince them to let her drop out of school and move to Los Angeles. When casting directors kept sending the naturally blonde Stone for entirely inappropriate cheerleader-type roles, she dyed her hair brown – and then, when she was cast in her first film, Superbad, turned herself into a redhead: anything to stand out from the crowd.

You have to say it's worked. Still only 22, Stone has just seen the back of a remarkable summer. First, there have been two bona fide hits – the Steve Carell comedy Crazy, Stupid, Love (global box office $136m and counting) and The Help, the adaptation of the best-selling novel by Kathryn Stockett that's the sleeper hit of the season (taking $164m in the US alone). Then there was that watershed in any actor's career, a cover shoot for Vanity Fair – in a particularly fetching striped bikini. "It still boggles my mind," she reflects, widening those almond-shaped green eyes. "It feels like it didn't really happen. You think: 'Why me?'"

She even laid the groundwork for what will surely be the biggest hit of her career to date with a visit to San Diego's Comic-Con (or "the Con", as she calls it) ahead of the release of next year's blockbuster reboot The Amazing Spider-Man, co-starring Britain's Andrew Garfield as the web-spinning superhero. A veteran of the famed fanboy convention – "it wasn't my first rodeo," she laughs, explaining she went for 2009's horror-comedy Zombieland – she enthuses about the fans who welcomed her casting as love interest Gwen Stacy. "That kind of passion is one of the most fun reasons to be involved with something like Spider-Man."

Then again, since Stone became the object of geek affection in Superbad, she has been a poster-child for the nerd crowd, flogging her goofy charms in films like The House Bunny, The Rocker and Easy A. Her skills as a comedienne have certainly got the respect and attention of her co-stars.

"I remember being with Bill Murray on Zombieland," says Woody Harrelson. "He was like: 'That girl is just gold – everything that comes out of her mouth. An incredible improviser.' It's really rare that you see a really funny, beautiful woman, who really just has the whole package. She's got it all."

Today wearing jeans, brushed-suede boots and a forest green sleeveless blouse, Stone certainly gives the impression of a girl who can't quite believe that she's got it all. She's baffled by all the press attention.

"If I'm being given an opportunity to say something and I've got nothing to say, then what am I doing? It concerns me... if I don't find my voice. I don't ever think that I should be political. I don't think I ever need to extend those viewpoints. That is so personal. And everyone should be making their own decisions, and I don't need to influence anyone. I'm an actor. What can I influence in that sense?"

In person, Stone is affable and genuine, the sort you can't imagine going off the rails on the Hollywood party scene. But underneath it all, there's a determination to be taken seriously. Right now, she's filming The Gangster Squad, which purports to tell the story of the LAPD running up against notorious gangster Mickey Cohen.

"I've got my 1949 nails on," she grins, waggling a flash of red in my direction. Featuring as a "sharp-tongued siren" caught in a love triangle, it means going head-to-head with Sean Penn, who plays Cohen, as well as reuniting with Ryan Gosling, her Crazy, Stupid, Love co-star. "It's pretty damn cool," she drools, with good reason.

Still, it's The Help that has proved Stone as more than just a comic star. Featuring a predominantly female ensemble cast, Stone takes the de facto lead – Eugenia "Skeeter" Phelan, a would-be journalist living in Jackson, Mississippi, during the Civil Rights movement era in the 1960s. Deciding to pen a book about "the help" – the black maids who cook and clean for their white employers – Skeeter's book causes a storm in their segregated community, where women such as the awful Hilly Holbrook (Bryce Dallas Howard) campaign for their domestics to use separate bathrooms.

Much like Skeeter's book, which becomes a word-of-mouth hit, the film itself has gradually grown in popularity – though Stone is unsure why it touched a nerve. "I think it might be because our culture has become so wild about escapism. So many movies are about the location it's taking place in, or the stunts and the explosions, which I'm all fine with, I love escapism as much as the next person. But I think people also like a good old-fashioned story. And this has so much within it. Just for some reason, this story has struck a chord with so many people. You'd be hard-pressed to explain it." Part of her preparation was to watch the six-part documentary series Eyes on the Prize.

"It was incredible," she drawls. "It was so enlightening and horrifying reading about the Jim Crow [racial segregation] laws, which I had no idea existed, and realising just how separate everything was. It was all new to me – and thank God I know it now. I think Eyes on the Prize should be required viewing in schools, because just to appreciate how far we've come has changed my whole life. "

Interestingly, Stone was shooting The Help when she found out that she won her role in The Amazing Spider-Man; not easy when her co-star, Bryce Dallas Howard, played the same character in Spider-Man 3.

"She was maybe the first person that came into my trailer. She banged on my door and said [adopting a rather nasal accent], 'the internet is saying that you are Gwen Stacy'. And I had just found out. They tell you that you're going to play Gwen Stacy and they say, 'it's going out in a minute and a half'. I had 90 seconds to go like this [she hyperventilates] and then it was all over the internet. So two minutes later, Bryce was like: 'Hi! Is this true?'"

In some ways, you might say winning the female lead in a blockbuster like this is the ultimate vindication of the Project Hollywood presentation. Born in Scottsdale, Arizona, and a regular of a regional youth theatre group in Phoenix from the age of 11 (The Wind in the Willows was her first play), it didn't take long before Stone had her sights set on Tinseltown. With her father a "self-made man", who started his own contracting company up in 1986, she estimated that to argue her case, she needed to meet him on his own terms. "A presentation is the way to get your point across. I was definitely my father's daughter on that one!"

With her parents' backing, Stone moved to Los Angeles when she was 15, living in an apartment with her mother, while her father and younger brother stayed in Arizona. Home-schooled, so she could audition in the day, Stone joined the legions of other young hopefuls attending brutal cattle-calls. Her "rock bottom" moment, she says, came when she tried out for the NBC sci-fi show Heroes, only to overhear the casting directors tell the girl before her "on a scale of one to 10, you're an 11". Out of the room came Hayden Panettiere – who ended up with the role of cheerleader Claire Bennet – and Stone went home, mortified.

Fortunately, she got Superbad and it changed her life. "I was still dependent on my parents and Superbad happened right before I was 18, and I became financially independent. So it was like, 'thank God!'" Since then, she has gradually watched her anonymity disappear – a process she's still getting used to.

"When people say something, it's really nice. But when people whisper or point, and you feel like you're a zoo animal, then it's scary and odd, because it's alienating." Together with her girl-next-door looks, Stone still seems like one of us, a starry-eyed fan who still loves to read celebrity interviews in newspapers and magazines.

"I'm not one of these people that must disassociate themselves from it, or has to cut it off," she says. "Other than I get addicted to it, so I have to do it in moderation!" Likewise, she took herself off Facebook. "I get addicted to the internet. I have a Twitter account. I look at it a lot, but I don't tweet. I'd be terrified that I'd say something and never be able to live it down." That's hard to imagine; Stone is far too in control for anything as careless as that.

'The Help' opens on 26 October