Arriving hot on the heels of an incendiary turn in Harmony Korine's Springbreakers, Vanessa Hudgens's latest role as a drug addled Anchorage-based prostitute seems certain to bring the guillotine down on her reputation as America's Sweetheart. The Frozen Ground, a chilly Alaskan thriller based on the real life hunt for serial killer Robert Hansen, sees Ms Hudgens caught between two titanic thespians – good cop Nicolas Cage and evasive killer John Cusack – and working for 50 Cent's mullet-wearing pimp.

This, notes Hudgens, as we meet in a London hotel, was a Brave New World for a girl who shot to fame as Gabriella, the prettiest face of High School Musical.

“I’ve never played a prostitute before. I’ve never played a stripper. I’ve never played a drug addict. I’ve never done anything like this -- on camera or off. The first time I’m on the pole in the movie is the first time I was on a pole. Me and the director Scott Walker didn’t even discuss it before. I wanted it to be raw. I wanted that to work for the character.”

Was she really as cold as she looks for most of the movie?

“Oh yeah. I froze my ass off. One night we were shooting it was negative 10. I was sure I had frostbite and that I was about to lose toes. I couldn’t feel my feet. It was extreme. And uncomfortable. And useful for the part.”

In the end, her lack of expertise and all that shivering do indeed coagulate into something impressive onscreen. The young actor explains that the project -- which brought her into contact with Hansen’s only surviving victim -- was all about authenticity.

“I spent an entire weekend with Cindy, which was a great opportunity to pick her brain. Now I know about her earliest memories right up to where she is now. I wanted to make sure I had all my facts straight. I read around the case as well. I had a clear view of what happened.”

How far did she get into serial killer literature?

“Not very. Not at all. This movie was all the psychology I could handle. What was going on onscreen was more than enough detail for me. That was disturbing enough. I’m not reading any further.”

She may have left High School Musical behind. She may have embraced a series of controversial and decidedly un-Disney roles. It's true that she favours The Beatles, Skrillex, Wu-Tang and Atoms for Peace over the autotune pop we've come to associate with her alma mater. Yes, she loves Quentin Tarantino and has sat through all of Harmony Korine's Trash Humpers.

Still, one couldn't comfortably argue that Vanessa Hudgens was anything other than squeaky clean. Looking at her up close, an estate agent might say she was "impeccably appointed". Dressed in an exquisite and elaborately embroidered red and gold suit, she has left no hair has been left behind when executing her perfect up-sweep. Her skin is radiant to an otherworldly degree. Her answers are sunny, polite and smiley.

“I’m a very enthusiastic person,” she says. “I’m passionate about what I do. I have a love for it. I’m able to stop doing a character and pick it up the next day without carrying darkness around with me.”

Vanessa Anne Hudgens was born in California to a fire-fighter dad and a secretary mom. She was raised Catholic and was frequently homeschooled to accommodate her aptitude for musical theatre.

“All of my grandparents were musicians,” she tells me. “But I never met any of them. I was a really shy and a really introverted kid. The only way for me to come out of my shell was as an entertainer. Singing and dancing was something I could hide behind. Once I was on that stage it wasn’t me anymore.”

Were her parents worried when she got mixed up with show business?

“Oh yeah. My mom still wants me to go to college. Even now. They were against the idea. It worried them that it was such a competitive industry and that I was a very fragile child. I was shy. I kept to myself. It didn’t seem like a good fit at all. It was a total contradiction. They allowed me to pursue it against their better judgement.”

From the age of eight, Hudgens became a regular in local musical productions. Entering her teens she had already appeared in am-dram versions of The Wizard of Oz, Carousel and The Music Man and several commercials. Does she remember her first time on a set, I wonder.

“Oh yeah. I was nine. I was in a commercial for Travelodge. I was singing and dancing with the Travelodge bear. I thought it was the coolest thing ever.”

Officially, the Hudgens narrative has it that she shot to fame as a shiny teen-star then struck out on her own with ‘shocking’ roles in Sucker Punch and the incoming Machete Kills. It’s often overlooked that her first big break was not with High School Musical or the Disney Channel. Instead Hudgens first came to our attention as part of the cast of Catherine Hardwicke’s girls-gone-wild drama, Thirteen. Was she old enough to see the final cut when it was first released.

“It’s funny,” she laughs. “You take what you want from things. I watched it. But I was very naive at the time. I really was 13 when we made that film. So all I got out of it was ‘whoa, these girls are crazy’ and also I wanted my belly button pierced. I did get it pierced but not until years later. I didn’t have a clue.”

Surely being clueless and painfully shy left her ill-equipped for the stardom bestowed on her by High School Musical. Being one half of the show’s onscreen-offscreen golden couple – Zac Efron provided the other part – and being the face that launched a thousand pencil cases must have been tricky?

“It was definitely overwhelming,” she nods. “The only thing that made it bearable was that I wasn’t alone. I had my cast mates to get me through it. We were all in a state of shock together. None of us could have anticipated it. It’s just not something that happens every day. Or ever. But together we had moments when we could just hang out and be kids -- in a group. It was a very well rounded way to grow up despite what you might think.”

The official Hudgens story – or the one, she points out, people like to project on her – tells off a girl unleashed from Disney Channel servitude to go wild with such maverick talents as Harmony Korine and Robert Rodriguez (director of Machete Kills). She flatly denies this is the case and is quick to defend her former employers at the House of Mouse.

“There was so much creativity involved in High School Musical. A bunch of it. Creating those characters. Dancing. Singing. Using your voice and your body. It was really expressive. There was a more to it than just acting.”

Was there any pressure – either from within or without – to behave like a Disney role model?

“Not at all. I am the way I am. I love doing what I do. I got to where I am being the person I am. My personal life is my personal life but there’s nothing I need to hide. I’m the person I seem to be. I believe in staying passionate. Be yourself. Strive for the best. I’m not ashamed of that. It’s an awesome thing to share with young kids. And I love kids. I love my young fans.”

Since Springbreakers has she noted a shift in her demographics?

“Definitely. I definitely have a new fan base. A guy in his thirties stopped me yesterday. He sees me on the street and he says ‘Vanessa Hudgens? That’s so funny. Me and my friend were just talking about you. You were great in Spring Breakers. Okay. Bye.’ And then he walked on.”

She laughs: “I’m used to kids running up and looking for a photo and an autograph. Now there’s a whole coolsville thing going on.”