Actress Rachel McAdams. Photo / Getty Images

Rachel McAdams found fame alongside Lindsay Lohan in Mean Girls — and got so freaked out by Hollywood she nearly quit. Now she’s navigating the red carpet on her own terms, starring in one of the year’s biggest TV shows, True Detective, and a new box office hit alongside Jake Gyllenhaal. She talks to Katie Glass.

Could the careers of two actresses have gone in more different directions than those of Rachel McAdams and her Mean Girls co-star Lindsay Lohan? After the 2004 film became an instant cult classic, Lohan and McAdams quickly became Hollywood's most sought-after starlets. But while Lohan, ironically cast as sweet, clueless Cady, grew up to become a Sunset Boulevard wild child, later redeemed by Oprah, McAdams took a different path. Having played the prom-queen nightmare Regina George, she skipped off to rom-com land to play dreamy crushes, deliberately swerving the limelight when she could.

On the back of Mean Girls' success, McAdams appeared in three blockbusters in 18 months: The Notebook, The Time Traveller's Wife and the frat-tastic Wedding Crashers, which has grossed more than $200 million at the box office. But as the clamour grew, she did a sudden about-face, turning down roles in The Devil Wears Prada, Casino Royale and Mission: Impossible 3. Then she walked out of Vanity Fair's Oscar-season cover shoot, also featuring Scarlett Johansson and Keira Knightley, when she learnt they were to be photographed nude. Following that, she decided to take a year out to "regroup". For a while she disappeared.

Since her return, her too-careful approach has led, arguably, to some forgettable roles. But this year she's ready to try something different.

McAdams tiptoes around the corner of Culina, the Italian restaurant at the Beverly Hills Four Seasons Hotel, in a white-and-blue minidress, tottering awkwardly on high heels. She is tiny, bird-like. Perching on a chair, she orders english breakfast tea with skimmed milk, and a seafood salad "without prawns", which she spends the next 90 minutes picking at. She is wearing too much makeup from a morning spent doing promotion. Still, up close, she is beautiful. Her hair is styled in short, choppy blond curls, which frame her fragile features, and she has creamy skin and sparkly eyes. She looks a decade younger than her 36 years. Then she flashes that megawatt beam, the smile that saw her hailed as the next Julia Roberts, and I instantly see why she became famous.

She is engaging, thoughtful and intelligent company. She sweetly asks about my jetlag and later invites me to a gig by a band called Jim and Sam. "They're so cute. They're a couple, they just play magic, simple stuff."

It is her role as the uncompromising, dark-edged sheriff Ani Bezzerides, in season two of HBO's TV drama True Detective (alongside Colin Farrell and Vince Vaughn), that could be the making of her. The Emmy-nominated series has the potential to turn her from rom-com star into a far more serious prospect, just as it helped to reinvent the former cast member Matthew McConaughey.

The first series of True Detective proved a watershed moment for television. A genre-defying, serial-killer police drama, it combined a richly linguistic script, charismatic performances and the lush backdrop of Louisiana's swamps to create a poetic noir masterpiece. It came at a time when television has been transformed - with more developed storylines than films can offer, and iconic roles (think Kevin Spacey in House of Cards). Competition for the new series was fierce, with Rosario Dawson, Jessica Biel and Keira Knightley allegedly considered for the role.

McAdams says she is drawn to complex characters more than just gratuitously "strong women". "They don't always have to be kick-ass women, just interesting characters. As long as there's something to sink your teeth into ... you never want to be bored in a role or else you'll be bad."

It was this aspect that she loved about her portrayal of Bezzerides, who has all the classic tropes of the work obsessed, uncompromising, hard-drinking detective with a dark past, more often represented in male cop characters. "She's dealing with a difficult childhood. She has vices she turns to, to decompress from her life, which is fairly full-on. She's probably not the healthiest cat!"

This time, the new series is set in LA and based around the murder of a corrupt city manager: it's edgier, more urban. She impresses as the hard-assed cop trying to negotiate with patronising men. Tightly wound, offish, with frazzled hair and no makeup, she's a far cry from her love-interest roles. "When you play a leading lady, you have to play someone who's accessible. It was great to be able to shed that skin and play someone who doesn't suffer fools gladly and was focused on her work. I don't know what people will make of her. I know she wouldn't care," she grins.

To prepare for the role, she rode with the Ventura County police department and the LAPD. "It was exciting. It was crazy." But she also enjoyed the depth of characterisation the lengthy TV series allowed. "I had time to marinade and get to know her. Her arc was much more extended than it would be in a film." For a programme accused of having a "woman problem" in its first series, the introduction of McAdams could be just what it needs.

She loves researching her parts: "It's an excuse to go take a class." One of the things she likes about acting is "I get to live many, many lives". She'd love to take on a transformative role - such as Renee Zellweger in Bridget Jones or Charlize Theron in Monster. She may not have posed nude for Vanity Fair, but "that was very different - I wasn't playing a character, it was an exposé on us as actresses, but as a character, people have to believe you are that person, so sometimes it takes more to get there."

What are her limits? "I can't think of anything," she considers, then laughs. "No one's ever asked me to knock my teeth out or anything."

Which is lucky, because she also stars in Southpaw, a boxing drama in which Jake Gyllenhaal plays the role of a boxer and she's his wife. McAdams isn't involved in any of the fight scenes, but she trained with Gyllenhaal, although not as intensively - his six-hour, 2000-sit-up workouts became notorious, and took him from indie-slim to super-ripped. While shooting, she gained "a great deal of respect for boxing as a sport", although "at the same time [I have] conflicting feelings about how violent it can be, especially at a certain level where kids are just starting out. You can get destroyed in a fight and never be able to fight again."

McAdams has another new release coming up: she plays an investigative reporter from the Boston Globe in Spotlight, a film that casts a light on a Catholic church sex-abuse scandal, which made headlines after reporters at the Globe uncovered child abuse within their local Catholic archdiocese. She was shocked by the scale of the abuse and by the fact that it was still being covered up as recently as the early 2000s.

"It's a story you can't tell enough - it's easy for things to slip back into the shadows. Victims still haven't seen retribution to this day." Having spent time shadowing the real-life reporters she was portraying, "endlessly bugging them", she worries that "this kind of reporting is slipping away - the desire and the money just aren't there as much any more, and it's so incredibly important that it continues".

McAdams grew up in the small town of St Thomas, Ontario, the eldest of three. Her father, Lance, was a truck driver; her mum, Sandra, a nurse. Her grandmother looked after her while her parents were at work. Her dad would pick her up in the evening and take her to fast-food joints. She was 7 when she wrote her parents a letter telling them she intended to become an actress. At 12 she went to an acting camp, and progressed to a degree in theatre at York University in Toronto. She "never in a million years imagined" she'd end up working in Hollywood. "LA wasn't even a blip on my radar."

The speed at which her career took off explains why she was so thrown by it. "I got a little freaked out. I didn't quite know what I was getting into. It felt like I was being swept up by this current and I wasn't sure what I wanted out of it. I got worried about being typecast or suddenly doing only blockbusters. I felt like I wasn't on solid ground for a bit there, and I wanted to check back in with me."

She went backpacking around Ireland and came back with a "reaffirmation of wanting to work with great people", "try new things", and "not do what was expected of me".

Although she's had a green card for years, she still lives in Toronto. She has never been tempted to move to LA - she auditions by Skype and travels for work when she needs to.

She prefers a simpler life than that in Hollywood's la-la-land and likes to potter in her garden, cook, play Frisbee and catch a movie at her local cinema. "I have to fill my cup back up sometimes and get back to normal life if I'm going to portray normal life," she says.

In the past, McAdams has complained about the scarcity of interesting screen roles for actresses, telling one interviewer: "Hollywood scripts aren't great ... It's like the girlfriend, the wife, daddy's little girl." Now, she is optimistic: "It's changing. We aren't as taken with the cookie-cutter. And people are enjoying being challenged."

Still, when I ask how many scripts would pass the Bechdel test, which requires a film to feature two normal female characters having a conversation about anything other than a man, she laughs: "Not tons! There are fewer great female roles [than male] and a lot of talented, strong actresses all fighting for them."

The revelation in the leaked Sony emails that Jennifer Lawrence was paid substantially less than her male co-stars was, says McAdams, "super-shocking". Yet she seems ambivalent about it: "It happens in other jobs as well. I try not to get mired in it too much. I have to remind myself that every single role isn't going to be the part of a lifetime."

Aloha, out earlier this year in the US, might be a case in point. The rom-com fared badly with critics, although McAdams says she's tried to adopt "a Zen attitude about the final product".

She claims she didn't read the leaked emails sent by Amy Pascal, then co-chairman of Sony Pictures Entertainment, which revealed rows over script rewrites, expensive reshoots and Pascal's disappointment with Bill Murray's scene. "I felt bad for her." She's sanguine about Pascal's criticism of some actors. "That's just human nature - we shouldn't hear about it. We would all be grilled, skewered and charbroiled by the public if all of our emails were out there."

She has a mixed relationship with celebrity, she says. "You want to keep working, but you don't want it to get larger than you are."

During our meal, the waitress recognises her and starts gushing: "Oh, you're so cute! I had to tell you that! I loved you in The Notebook!" McAdams rounds her shoulders submissively, smiles sweetly, and looks embarrassed, "Oh, thank you! It's so nice to see you, too."

Does that happen often? "Not quite like that," she says, modestly. "She was particularly nice."

She says she has been nervous going through Customs ever since a female customs officer told her she didn't like her films. "I couldn't say anything in case she threatened to deport me!" McAdams had pink hair at the time, and the woman told her: "Don't dye your hair that colour and don't make any more stupid movies."

She certainly has the talent; now, perhaps, if she proves herself in True Detective, she'll have enough opportunities to act on it.

As the strapline accompanying her image on the billboards of Los Angeles goes: "We get the world we deserve."

True Detective series two screens on SoHo Mondays at 5.30pm and 8.30pm. Southpaw opens on August 20.

- Canvas