Emily Blunt: Sicario role inspired by real female FBI officers

In crime drama Sicario, Emily Blunt plays the lead role of an FBI agent who joins an elite force to combat a drugs warlords on the US-Mexico border.

For almost the entire film, she is the only woman on screen.

"It's something you don't see in cinema," says the British actress. "Even though there are a lot of women in law enforcement, we just don't make films about them."

Blunt says her character, Arizona FBI agent Kate Macer, is the film's moral compass.

At the beginning of Sicario - which in Mexico means hit-man - Kate uncovers a horrifying "house of death" connected to a Mexican drug cartel. She is then recruited to a covert black-ops mission headed by mysterious Colombian Alejandro (Benicio del Toro) and special agent Matt Graver (Josh Brolin).

Blunt had no back story to work on for Kate "except that she just got a divorce and she needs a new bra", so she fleshed out the role by talking to real-life female FBI agents.

"I based the character on one in particular who had an inner steeliness," she says. "She spoke very softly and she was quite shy and yet she worked on a kidnap response team.

"It was a very physical job. She worked with these big men on the Swat team and was unfazed by it."

While promoting Sicario at last month's Toronto film festival, Blunt revealed a potential backer had wanted screenwriter Taylor Sheridan to rewrite the lead character as a man in order to attract further investment.

Had that shocked her? "Sadly, I'm not surprised," she says. "But I'm thrilled by Taylor's reaction, which was to consistently walk out of those rooms. And that's why it took him a while to get the film made.

"I don't think it's a blip. It happens a lot. Numbers are crunched on films that have done well. When you do that, you are making films that are derivative of something else."

But she remains optimistic that the Hollywood landscape might be changing, citing recent the performances by Charlize Theron in Mad Max: Fury Road and Rebecca Ferguson in Mission: Impossible - Rogue Nation.

Blunt says: "There are a lot of films that are coming out that embrace stronger roles for women - more complicated roles, not just about being strong or having a gun. That's so boring."

Blunt and Ferguson are about to work together on the film adaptation of the bestselling book The Girl on the Train.

Blunt will play the girl of the title - an alcoholic divorcee who fantasises about a couple she sees from her train. The film, directed by The Help's Tate Taylor, is set for release in 2016.

"I'm about to play a blackout drunk," says Blunt, "and what I think readers have responded to with that book - and hopefully the film audience will too - is less the thriller aspect of it but the portrayal of these three incredibly damaged women, which I think is more interesting to people."

Last year, Blunt's big screen appearances included musical Into the Woods and sci-fi thriller Edge of Tomorrow.

She is an actress who bounces comfortably between genres. She came to international attention opposite Meryl Streep in The Devil Wears Prada, and her other film roles include The Adjustment Bureau, Salmon Fishing in the Yemen and Looper. She played the title role in The Young Victoria.

Her acting career started on stage, with Blunt making her West End debut in 2001 opposite Dame Judi Dench in The Royal Family. Although she hasn't been on stage for more than a decade, Blunt is keen to "do a new play" in the US, where she recently became a citizen.

Is there any genre that has eluded her? "I haven't done a Western... but Sicario... is kind of a Western. I try not to base my ambitions on genre or type of movie. I try not to strategise the next move, The roles I take on are the ones I'm surprised by and challenged by."

Sicario's Kate Macer is just such a role. Blunt says director Denis Villeneuve's film will stay with people.

"That's so thrilling to me," she says. "Often people leave a cinema and they don't discuss a film because they've seen something derivative. I think this will be a film people will discuss for days afterwards."

Sicario is released in the UK on 8 October.