Heart and soulmate

"It's a good boom," she laughs. "It's not aggressive."

Having been the screen face of Stieg Larsson's leonine heroine Lisbeth Salander and a Ripleyesque astronaut in Ridley Scott's Prometheus, Rapace often finds herself reassuring strangers that she is a pussycat, really.

"People say to me, 'You're so funny, you're laughing a lot, it's so nice to see you smile'. Why wouldn't I smile? In real life I'm happy. I do smile a lot. I've never felt depression. I'm not a dark and heavy soul, but people think when they watch my films, that I'm this kind of moody and angry person. If that was me, I would probably not do these kinds of films."

Rapace is indeed a good spud when we meet in a Soho hotel. For a long time, she shied away from interviews. An early encounter with a Swedish tabloid when she was 16 and starring in a soap opera left her feeling bruised and used (long story, but the resulting headline, she recalls, was "I want to have a sex scene with Johnny Depp"). Years later, as her profile grew abroad through such blockbusters as Sherlock Holmes: A Game Of Shadows, she was still reluctant to do interviews, feeling her English was not up to it. Now the multilingual Rapace is finding her voice.

The Drop, which premiered at the London Film Festival in October, confirms the 34-year-old's reputation as the doyenne of damaged souls. Adapted from a short story by Dennis Lehane (Mystic River, Gone Baby Gone), with the screenplay written by him, this Brooklyn-set tale stars Tom Hardy as Bob, a shy young barman working for his cousin Marv (James Gandolfini). When Bob meets the vulnerable Nadia (Rapace) it is love at first sight - for a dog.

Directed by Michael Roskam, helmer of the Oscar-nominated Bullhead, The Drop is the kind of end-to-end entertaining picture you thought they stopped making after The Sting. Despite the hot-as-lava cast, the real star is Rocco, the pit bull terrier puppy that Bob rescues from a dustbin outside Nadia's house. When pictures of Hardy playing with the pup on set arrived on the internet, they made cat videos look unpopular.

To break the ice, then, I opt for some dog banter, hoping for some fluffy tales of waggy tails. Was it a treat to work with the pup? From the way Rapace's eyes fill up I soon twig that this was perhaps not a smart move.

"I had a complicated relationship to dogs," she begins, peering out of a mane of Blondie blonde hair. Growing up on a farm in Iceland with her mother and stepfather, the young Noomi was inseparable from her dog, Raven. "He was this big black dog, kind of a bad-ass bastard, mixed breed, grumpy, angry, quite aggressive, but he loved me. He was always by my side. He was a fighter, tough. He was hit by a car once and had his leg broken. It healed but in a weird way, so he was limping but still going strong. Then one day when I was 12 he was hit by a car again and he died.

"For two weeks I just wanted to die. I thought, 'I can never heal, I can never come back from this.' I had lost my best friend. I was completely devastated. Then I kind of closed my heart. I thought, 'I can't have a dog again, I can't take that again.' I was lonely anyway, I didn't have a lot of people around me, so it was a big thing for me."

As it turns out, there is a happy ending to this story, one Rapace found in a scene in The Drop where she is watching television, with Rocco on her chest. "He fell asleep and I just listened to him breathing. I thought, 'Wow, he's kind of healing me.' It took me back to my childhood. That's the beauty of dogs. It's like a Band Aid, like medicine, like someone cuddling your broken heart."

When it comes to choosing films, she starts with the director. Otherwise, she says, it is too hard. "I have no limits. I go as far as is needed. And I will only do that if I feel like I'm in the hands of someone who understands what I'm trying to do." Indeed, the last time I spoke to her was two years ago when she had just finished making Babycall, a harrowing drama about a young mother terrified she is losing her mind. Rapace had found the part physically and emotionally draining.

Like her co-star Hardy, with whom she also stars in the forthcoming Child 44, an adaptation of Tom Rob Smith's bestselling thriller, Rapace is an all-or-nothing kind of actor. "I never want to stop doing that. I don't want to start to make safer choices or [think] 'This is a good money job'. I want to stay on this side. I want to stay brave, even though it is not always the easiest thing. If I have one team player, a kindred spirit, then I know I'm safe. It doesn't need to be everybody, I just need to have one soldier who is fighting my battle."

In The Drop she had at least three - Hardy, Gandolfini and Roskam. Watching Gandolfini in what was to be his last film turned out to be a joyful if poignant experience. "He's so brilliant at capturing the sadness, the bitterness, the broken dreams of this man. I went out of the cinema thinking, 'Wow, that was beautiful. What a performance.'"

Rapace was born in Sweden in December 1979; her mother is the Swedish actress Nina Noren and her father, a flamenco singer, died from cancer in 2007. They only began to get to know each other shortly before he passed away. She began acting as a child in film, on stage and in television, finding domestic fame early on. When she was cast as the lead in The Girl With The Dragon Tattoo, the first in Larsson's Millennium trilogy about a computer hacker taking on the Swedish Establishment, her fame went global. She was terrified about taking the part.

"There were so many people who loved the book all over the world. It's impossible to satisfy people because they all have the dream, the picture, of Lisbeth in their heads. To bring her to life, give her a soul and a face, how is that possible? At one point I thought, 'Okay, I have to just ignore all that. I have to go into my own zone, close the door to the world, find my Lisbeth, use myself.'"

More than a year passed in filming, locked in her cocoon. Then it came time for the premiere. "I was shaking, thinking, 'Oh God, they are going to kill me now.' I expected the worst. Then I started to realise they liked what I did, but it took me a long time to take in the fact that people accepted what I did with her."

She once described Lisbeth as a "cracked soul". I wonder why Rapace is so adept at playing such characters. Is she one herself, or has she known a few? There is a long pause.

"I have a soul that cracks, but it is not cracked. It is not broken into pieces, but it has scars," she says. "I have a great understanding for the complications of life, being a person struggling. I've seen up close how someone who is actually a strong person can fall. I don't judge people. What happened, what was the moment when it all kind of exploded? If you can trace it back to that … that's what I'm trying to do with all my characters."

With our time running out, I turn to decoding Rapace through her jewellery, much of it made by a friend, Maria. "I like to wear stuff ... It feels like it's a good protection for me," she says as she talks me through the pieces, chief among them a bracelet inscribed with the birth date of her son, Lev, now 11. She became pregnant at 22, just before she landed a big part, and was amazed when people wondered if it was a good idea to become a mother so early. Rapace was having none of it. "I've always done things my way. I'm not driven by fear. I've always been quite convinced that you can do pretty much anything if you know what you want."

Rapace and her ex-husband, fellow actor Ola Rapace, have remained friends since their 10-year marriage ended in divorce in 2011. They are bringing their son up together, which makes for plenty of plane trips for Lev. Rapace, whose sister also helps out, has just bought a house in London, so things should settle down. "When I have my situation here completely sorted, I think he will go back to school here. It's a bit of a puzzle, a lot of logistics. But we help each other as much as we can."

She describes her "cool" son as "more like an old soul, a little gypsy". What does he think of mother's acting career? "He's quite tough on me," she laughs. "It's not easy to impress him. He loves Sherlock Holmes." She wants him to have as normal a childhood as possible, or as normal as it can be when mum is a movie star.

"I don't want him to grow up in a world of celebrities, a privileged, odd situation where he is not connected to real life. It's important for me to try to stay and have a life around him that is very normal. It's something I have to remind myself. I was fighting my whole life, there was nothing for free. I grew up without money, grew up on cornflakes and milk, and I have to keep in mind the situation for him is so different. Flying business class and having a crew around you constantly, that's not normal."

Fortunately, that old soul of his keeps him straight. "If you ask him shall we go to this nice fancy restaurant, or do you want to make something here at home, he'll say let's just do pasta and pesto. He's not so blown away by the whole circus around me."

Should work on the sequel to Prometheus pick up pace ("That's the plan"), the boom bang a bang around Rapace will only grow bigger. Maria had better start working on more necklaces.

The Drop opens in cinemas on November 14