Few film debuts are as electrifying as Alana Haim's. The star tells Georgia Humphreys about making the move to the silver screen.

When Alana Haim opened an email from film director Paul Thomas Anderson a few years ago, she had no idea it would contain a script.

Specifically, a script for unique new film Licorice Pizza, written by Anderson with the now-30-year-old - the youngest of three sisters who make up American pop rock band Haim - in mind for the lead character.

"There was this untitled Word document that I opened, and it was the first script I had ever read in my life," recalls LA native Haim, who plays guitar, keyboards and percussion, and is fizzing with excitement talking about her acting debut over Zoom. "I mean, me and my sisters don't get sent scripts - we're musicians.

"I read it and all the scenes really just jumped off the page, and I couldn't put it down, and it was so exciting even just written; I was excited to see the film just be made."

Some scenes are based on real-life, from stories the star had told Anderson, who has directed music videos for Haim (known for songs such as The Wire), and has become a close family friend. But she still didn't expect to actually be in the film, she confides.

"Paul thinks that I'm crazy, like, 'Your name was on the script, a lot of the stories that you've told me in your life was in the movie, but you didn't think that I was gonna ask you?'

"But I would never just assume anything. I had hoped that maybe he would ask me to play Alana; I was just such a fan of it. And I called him very jet-lagged in London after I had read it, and we talked about maybe could I ever think about playing Alana and I was like, 'Of course! Are you kidding me?'

"Then I read it three more times after I hung up the phone with him because I was just so excited about it."

So, what is Licorice Pizza about? Well, it's set in San Fernando Valley in 1973, and follows Alana Kane (Haim) and Gary Valentine (Cooper Hoffman, who is the son of the late actor, Philip Seymour Hoffman).

Written and directed by Anderson - who's famous for Boogie Nights, Magnolia and Phantom Thread - we see Alana, who is in her twenties, meet Gary at his high school - it's picture-taking day, and she is working as a photographer's aide. The dialogue grabs you right from the start, as Gary tries to impress this alluring older woman with stories of him being a working actor, and a friendship begins.

As Gary tries his hand at being a budding entrepreneur, selling water beds, and opening a pinball arcade, Alana - who seems lost and unsure about her future - starts working alongside him, and they become closer.

It's an amusing, vibrant, and romantic watch, with particularly memorable scenes including Alana's own foray into acting, appearances from Hollywood stars in the shape of Sean Penn and Bradley Cooper, and plenty of tender and awkward moments between the two main characters.

At its heart, it's a coming-of-age tale about self-discovery and first loves - and Haim is receiving rave reviews.

Asked how surprised fans of Haim the band will be by her performance, the star laughs and says: "I mean, I'm just as shocked with them! I think they'll be very shocked because I've never done this before... Me and my siblings love making people laugh and making funny videos, but nothing to an extent of a movie.

"It's a major motion picture, and I'm just shocked still that Paul saw something in me, that he thought he knew that I can do this role and do Alana.

"But, yeah, it's going to be pretty shocking. My parents were the most shocked - my parents didn't believe it! And if my parents can't believe it, then literally no one can believe it."

Licorice Pizza is a bit of a family affair, as sisters Este and Danielle, plus both their parents - American-born Donna and Mordechai, known as Moti, who was born in Israel - also star in the film, playing Alana's family.

The Haims are Jewish and the hilarious Shabbat scene - when Alana brings a boyfriend to meet the family and chaos ensues - is based on true events (though in real life it was the middle sister, Danielle, and it was Passover, not Shabbat).

"It's fully a story that I had told Paul just through friendship," reveals Haim.

"We would tell funny stories all the time to each other about our lives and I remember telling him that story, and I had told it to him a long time ago.

"I remember I was getting on a flight to New York and he was like, 'Can you send me a voice note of that story that you told me about Shabbat dinner?'. And I sent him a voice note of me just saying it, and then getting the script and seeing, almost word for word, my depiction of the night was in it... It's so funny seeing it now."

And while all the cast is great to watch, it has to be said that Moti, in particular, is quite the scene-stealer.

"Oh, I know!" exclaims Haim. "He's incredible. And that's my favourite part of the movie, is having people watch my dad because he had no idea what he was doing - that was just fully improv.

"We knew the scenario, but there wasn't a script that was like, 'And now your dad will say this'; it was really just Paul talking to my dad and saying, 'Just see what comes out'.

"And my dad is so funny without even knowing that he's funny, which is the best part about it."

Licorice Pizza is in cinemas from today.