Before her breakout role as a saucy soccer player in the 2002 feel-good film Bend it Like Beckham, actress Keira Knightley was known to movie audiences as little more than the Natalie Portman look-alike who served as Queen Amidala’s decoy in Star Wars: Episode I-The Phantom Menace. Much has changed since then for the 19-year-old starlet, whose last few films have covered a diverse set of roles including a ballsy Lady Guinevere in King Arthur, Orlando Bloom’s tough-as-nails love interest in Pirates of the Caribbean and Juliet, the pined-after fiancée in Richard Curtis’ ensemble dramedy Love Actually.

Knightley’s part in the up-and-coming feature The Jacket – a psychological thriller due in theaters March 4 – is no exception to her already extensive slate. In the film, which also stars Adrien Brody (The Pianist), Kris Kristofferson (Blade) and Jennifer Jason Leigh (The Anniversary Party), Knightley plays Jackie – a troubled young woman living in a small town, scarred by the tragic death of her alcoholic mother years before and working a dead-end job as a diner waitress. Jackie is traveling down the same sad path as her mom – she keeps a crummy apartment, smokes and drinks too much, and has virtually no sense of self-protection. All in all, Jackie is a mess.

"It was an exciting, imaginative script, and a role I wanted to play immediately," recalls Knightley of reading The Jacket. "The other eight scripts on my pile were variations of the same pretty, uptight British girl, but Jackie was this damaged character who meets a guy going through trauma. It’s very rare that a film will show people who are in the process of self-destructing."

The guy who Jackie meets is Brody’s Jack Starks, a Gulf War veteran who – after taking a near-fatal bullet to the head which leaves him with amnesia – is committed to a mental hospital for the criminally insane when he’s wrongfully accused of killing a cop. Under the questionable care of the hospital’s Dr. Becker (Kristofferson), Starks – who once met a young Jackie by the side of the road while attempting to fix her mom’s car – is repeatedly injected with anti-psychotic drugs, forcefully strapped into a straight jacket and locked, for hours at a time, inside a dingy morgue drawer in the hospital’s deserted basement.

It’s here that The Jacket really gets interesting. While in the drawer, Starks is able to propel himself into the somewhat-near future. Although he’s literally trapped in the jacket (hence the film’s title), he simultaneously winds up in 2007 where he is hesitantly befriended by a grown-up, self-destructive Jackie. It is here and now, in the future, that Starks learns he is destined to die in a mere four days.

"When [Jackie] meets Starks she has nothing to lose, and she has no self-protection instinct," says Knightley when reflecting on her character. "She picks up a stranger in a car park, offers him a ride, then lets him stay at her apartment while she drinks and takes a bath. She is almost inviting harm in a reckless way."

While harm doesn’t befall Starks and Jackie as a couple, it did almost surface when Knightley first met with director John Maybury in regards to the role. According to the actress, who turns 20 on March 26, she traveled to London from the Dublin, Ireland set of King Arthur to discuss The Jacket. The trouble was that she had a debilitating case of food poisoning when she showed up at what turned out to be a lunch meeting.

"I spent most of my energy trying not to projectile vomit on these people I desperately wanted to work with," says Knightley.

Little did she know, though, that Maybury – who most recently wrote and directed the 1998 film Love is the Devil, a biography of British painter Francis Bacon – already had a preconceived notion about casting Knightley in The Jacket.

"I didn’t want Keira Knightley for the role," admits Maybury. "I’d met 15 to 20 young American actresses, and there were at least two or three that I thought would be terrific as Jackie. So, very reluctantly, I met with her. I knew she was an interesting, pretty girl, but that was it as far as I was concerned.

"The fact that she had food poisoning at the audition actually served to make her act and look even more Jackie-like," Maybury adds. "Then, when she read, she was excellent. I realized that she was a very intelligent girl and a very good actor. She comes across almost like a young Jane Fonda."

Just like Maybury, Knightley – who will shortly reprise her role as Elizabeth in Dead Man’s Chest, the Pirates sequel, as well as star in the up-and-coming films Domino and Pride and Prejudice – has a vivid memory of the fateful day during which she was offered her multifaceted role in The Jacket.

"[Maybury] told me that he did not think I was right for the role and he didn’t want me," Knightley remembers. "At that moment, I had nothing to lose. I declared that if I didn’t get the part of Jackie I could be stuck in corsets for the next 20 years, and asked him to let me read. He agreed, and promised [that] if he was convinced, he would hire me. We shook on it. I read the part, he gave me some notes, then gave me his phone number and offered me the job."

With a smudgy-eyed, self-destructive character now on her resume, Knightley – who was born and raised in England and once said that Katherine Hepburn and Vivien Leigh are among her heroes because of their perseverance – is good and ready to take the next step. With The Jacket about to hit theaters and three more films already under her belt, Knightley is sure to take Hollywood – and the world – by storm before she’s even 21.

The Jacket releases in theaters March 4.