Red hot: How Jessica Chastain became Hollywood's most wanted

You'll be seeing a lot of Jessica Chastain this year – and Oscar glory already beckons with her latest film, The Help. Not that her career needs any...

There is a giggle and a "Ssssh!" from the bedroom of Jessica Chastain's hotel suite. Her mother and at least one younger sibling are in town and, from behind a pair of frosted-glass sliding doors, appear to be very much enjoying their stay at one of the more famous and upmarket establishments in Beverly Hills. The perks of Jessica's stardom are still new to them; for the time being, at least.

Chastain is perched in an armchair, drinking herbal tea. Behind her sits a pair of crutches. In front, an injured leg in the late stages of recovery from a motocross accident. It hurts, she says, showing off a small knee-high scar. But on the plus side, it also provides an easy talking point to enliven the various TV appearances, press junkets, and red-carpet interviews that are suddenly part of her daily working life.

To say that Jessica Chastain is an up-and-coming actress with a busy schedule is a bit like saying that the Civil Rights struggle, which is the subject of her highly-successful new film The Help, involved a bit of local difficulty in the American South. In an absolutely literal sense, it's perfectly true. But it's also what you might call a clattering understatement.

No fewer than four of her movies have arrived in cinemas so far this summer, including Terrence Malick's Cannes sensation The Tree of Life, in which she co-starred with Brad Pitt, and John Madden's thriller The Debt, where she played the younger version of Helen Mirren. They've been attracting terrific buzz. In fact, the Malick film won the Palme d'Or.

Continuing this roll, three more Jessica Chastain films are due out before Christmas. Among them is Wilde Salome, which sees her share limelight with a sometime mentor, Al Pacino. And in the New Year she will star with Gerard Butler in a Ralph Fiennes-directed production of the somewhat unfashionable Shakespeare play Coriolanus.

"It's crazy," is how she sums up recent months. "One moment, I'm completely unknown; the next, I'm driving through town and I'm on billboards for, like, three different films... The way I keep describing it is to say that I must be the first unknown actress that everybody is getting sick of. People don't recognise me when I walk down the street, but they'll hear my name and say, 'She's everywhere'."

At the age of 30, Chastain owes her sudden ubiquity to the vagaries of the movie business. She's been employed pretty consistently – in TV, film and theatre – since leaving drama school in 2004. Her co-stars have been some of Hollywood's biggest names, and her performances have attracted industry-wide buzz that has seen her compared to a young Meryl Streep, or Nicole Kidman. But until this year, only two of her movies had actually been released into cinemas – and they had pretty much sunk without trace.

"In the past four years, I have made 11 films, as well as a TV movie of Murder on the Orient Express, which was on the BBC," she says. "And then I've had to wait and wait. My poor parents! Ever since the start, I've been telling them that I'm working with, say, Brad Pitt or Ralph Fiennes. And then all this time, years and years just rolled on by."

The various delays are nothing to do with Chastain's lack of talent or marketability. They revolve, instead, around her choice of movie. She has worked twice with Malick, the famously ponderous auteur who has completed just five films in the past 38 years. And she has never been cast in a 'tent-pole' blockbuster, preferring instead to take quirkier independent projects which are harder to bring to market.

The extended anonymity has, however, come well and truly to an end with The Help. A movie version of the bestselling Kathryn Stockett novel, about black housemaids in 1960s Mississippi, it was released in the US in August and promptly became the summer's break-out hit, making more than $170m (£108m) at the box office, against an estimated budget of $25m (£16m). The movie is now at the centre of the conversation in advance of Oscar season.

Chastain supports the brilliant Viola Davis, Octavia Spencer, and Emma Stone in the film, a devastatingly successful tear-jerker which manages, despite its delicate subject-matter, to position itself just on the right side of saccharine. She plays Celia Foot, an emotionally wonky housewife in the Marilyn Monroe mode, with a vulnerability that adds texture and depth to a potentially monochrome character.

"Celia was about the hardest character to cast," says Tate Taylor, The Help's director. "A little to the right or a little to the left, and she'd be a caricature. We could be left with Jessica Rabbit. On the day she auditioned, I'd seen a bunch of actors who just weren't right. Then Jessica came in and read for the part, and just killed it. I was literally crying. Then she said 'Thank you', got up, and left the room. We were all just blown away."

Chastain is by no means a method actor. But she does tend to prepare heavily for roles. Prior to appearing in The Debt, in which she played a Mossad agent, she trained in Krav Maga, the martial art invented by Israeli special forces. For The Help, she read books and watched documentaries on the Jim Crow era, and put on several stone in weight to attain a Southern physique.

As a vegan, that was easier said than done. "I just started eating all the time," she says, during a minor foray into luvvie mode. "It was awesome, constantly eating big, big meals to stretch the stomach out. But when I got to the set, and we were about to shoot, I still wasn't as big as I wanted to be, so I got kind of intense. By the end, I was buying vegan soy ice-creams, microwaving them, and then just drinking it. I ate a lot of soy, because the oestrogen in it's supposed to makes you curvy."

Chastain's willingness to go the extra mile may reflect both the distance her career has travelled and her apparent determination not to become attached to the more ephemeral temptations of celebrity. The daughter of a fireman, whose mother is a vegan chef, she had a solid, blue-collar upbringing, somewhere in the commuter belt around San Francisco. Sweetly, given the increasing loftiness of her profile, she has thus far kept the identity of her home-town secret.

"My biography just says I come from northern California," she says. "It's ambiguous for a reason, because my family still lives in the area I grew up in, and we keep the fact that I'm in the entertainment business kind of quiet. So a lot of my mum's friends don't know. One didn't even know I was in a movie with Brad Pitt until she saw me in the trailer. It means that I'm able to go home and still be normal."

As one of five children, from a family which has no particular show business connections, the policy is also designed to prevent her four siblings from being overshadowed. "One brother's in junior high and a sister's in high school. And their friends don't even know, so no one tries to get anything from them," she says. "It takes a lot of work on their part. But I think it's a beautiful thing that my 12-year-old brother doesn't feel compromised."

Chastain's family has none the less been able to enjoy some of the high points of her career. Both her sisters and one of her two brothers trod the red carpet in Cannes this summer, for the premiere of The Tree of Life. Her second brother missed out, since he was serving in the armed forces. "He's in Iraq right now, actually," she says. "He's in the army, and also tries to keep my job quiet, but some of the boys have found out and given him the nickname 'Hollywood'."

Chastain first decided she was going to be an actress at the age of seven, when her grandmother took her to see a touring production of Joseph and the Amazing Technicolour Dreamcoat, starring David Cassidy. "She told me, 'Jessica, this is a professional play, which means people do it for a living'. I was really young, and when the curtain went up, there was a 10-year-old girl on stage as the narrator. And as soon as I saw the girl, I knew it was my job. I just knew it was what I was going to do."

As a teenager, she performed in amateur productions of Shakespeare around the San Francisco Bay area, using her mother's maiden name instead of her father's surname (Howard) because it sounded more actorly. After taking the female lead in a well-received Romeo and Juliet, she was advised by a fellow cast member to audition for a place at the highly prestigious Juilliard arts school in New York.

"It was a very long audition day in San Francisco, and I found out two weeks later that I was in. It was one of those moments when you know your life has changed completely. But then there was this panic about how to pay for it. I come from quite meagre means. We don't have a lot of money, and no one else in my family had ever gone to college, so it was a completely foreign idea. But I was very lucky, because the Juilliard is incredibly generous with their financial aid."

She was helped by a scholarship funded by Robin Williams, a famous old boy of the Juilliard. And her good fortune continued when, shortly before graduation, she attended a 'showcase' for final-year students in Los Angeles, and was promptly signed to a holding deal by John Wells, the producer of TV dramas such as ER and The West Wing.

She moved to LA, took up residence in Venice Beach, and began throwing herself into the whirlwind of auditions. At first, she found it tough: casting directors were unexcited by her blue-chip education, and (thanks to her red hair and relatively diminutive stature) were unable to neatly pigeonhole her. But after a while, she found a sort of niche playing eccentric characters in television drama series.

"In the first few years, I would look around auditions and realise that I wasn't the same as everyone else. So I don't think people knew what to do with me. But then I did a job on ER as a psychotic woman, and after that got a lot of jobs in TV where I wasn't the normal one; I played a lot of girls who had something off. Maybe they'd been the victim of some horrible accident. Or they were crazy."

Her big break, so to speak, came in 2006, when she was cast as the female lead in a production of Salome, playing at the Wadsworth Theatre in Los Angeles. Her co-star, and director, was Al Pacino. And the success of the play, which sold out after getting enthusiastic reviews, helped bring her to the attention of some of the city's most influential casting directors.

Soon afterwards, she was invited to fly to lunch with Terrence Malick, at his home in Texas. The meeting led to her being cast in The Tree of Life, a film which has been variously described as either a historic masterpiece, or pretentious guff (depending on your critical persuasion). Most critics plumped for the former, though since its release, the film's box-office performance has perhaps suffered because of the notoriously reclusive Malick's reluctance to promote it.

Chastain describes Malick as "the sweetest, most intelligent, nicest, most generous man I could ever meet", and has a sort of admiration for his ability to stay one step removed from the corrupting influences of show business. "He doesn't want to be famous. It's nothing to do with being annoyed by the press. It's because he's incredibly humble," she says. "And how can you make a film about humanity if people are constantly setting you apart?"

Taking a leaf from his book, she is determined that her future will involve ploughing a similarly elusive furrow. "I do try to be as mysterious as I can, especially with my private life, because the less people know about me the better," she says, regarding her current domestic existence (she is single). "I don't get recognised. I don't date actors. I just try to keep my life as simple as possible so I can go disappear." It's a noble ambition, but given her sudden ubiquity, getting Jessica Chastain to disappear may soon become an awful lot harder.

'The Help' opens on Wednesday