Ian McEwan, the acclaimed Booker Prize-winning English author, has seen many of his novels adapted for the big screen, but it was watching then 12-year-old Saoirse Ronan on the set of Atonement - the film version of arguably his most popular book - that stopped him in his tracks.
"Even then," he recalled, years later, "she showed an extraordinary ability to take control of the material, to morph from a sparky Irish kid into an upper-class English girl with cut-glass accent to match.
"She knew how to convey a particular form of inwardness, of an imagination running riot. She also completely charmed and hypnotised the set."
And she charmed Academy Award voters too by receiving a nomination for Best Supporting Actress, becoming, at just 13, one of the youngest in movie history to achieve such an honour. She lost out to Tilda Swinton, but she had made an indelible mark.
Fast-forward to 2020 and the Bronx-born star has been nominated for an Oscar yet again. Remarkably, at just 25, it's her fourth nomination, for her performance in another much-loved literary novel - Louisa May Alcott's Little Women.
Ronan has quietly become one of the most revered actors of her generation - and a figure who has made the transition from child prodigy to adult leading lady with apparent ease.
Hollywood is littered with child stars who failed to make it in the business once they reached adulthood.
One need only ask where Corey Feldman (Stand By Me), Haley Joel Osment (The Sixth Sense) and Henry Thomas (ET) are now.
But there have been no such difficulties for Ronan. She may have grown up on screen, but she has remained grounded off it.
And there has barely been a blip on the upward trajectory her career path has taken.
"Between 2010 and 2015," according to film critic Paul Whitington, "she had successfully negotiated that awkward bridge between child and adult acting, quietly impressing in films like Hanna, Byzantium and How I Live Now.
"Then, in the space of 12 months, she appeared in a remarkable string of quality movies that launched her career into full-blown stardom."
"It was intense," she told Whitington last month. "Everything was kind of changing for me and it felt like I was just sort of floating above my body that year, because there was so much going on.
"There was so much work, more than I'd ever done, and finishing it, and having the work turn out to be good, I was kind of like, 'Okay, that's the baptism of fire'."
Although born in New York - and still an American passport-holder - she was raised in Dublin and rural Co Carlow. With her father Paul, an actor who still works in the industry, it was not surprising that young Saoirse would gravitate towards performance.
She began acting professionally aged just seven and first came to prominence when she appeared in RTE's popular GP-set drama series The Clinic.
But it was beating hundreds of auditionees for the challenging role of Briony Tallis in Atonement that set her on the extraordinary run of films she has enjoyed since.
Ronan has credited dialect work she undertook for an aborted film around 2005 for helping with the audition for Atonement - and she must have wowed the casting director because film-maker Joe Wright had been on the lookout for a child who looked like Keira Knightley (who plays Briony's older sister in the film).
And the industry recognition has kept coming. In 2015, her portrayal of a homesick Wexford girl in Brooklyn - based on the Colm Toibin novel of the same name - won her a second Oscar nomination, this time in the Best Actress category. Then, last year, she was Oscar-nominated for her role in the coming-of-age indie film Lady Bird, directed by Greta Gerwig.
Her performance bagged a Golden Globe. And it's Gerwig who is at the helm of Little Women.
The book has been filmed eight times previously, but Ronan signed up when it was confirmed that Gerwig would be directing and she could play the part of one of literatures great feminists, Jo March.
Ronan has been prolific and it's that appetite for work that has made her become a better actress, she feels.
"The more you do it," she told the New York Times, "the more open you are to accessing feelings.
"I've gotten to a point in my work where I need to stand firmly with decisions I've made or feel free to go in another direction - even if everyone around me is telling me to do the opposite."
And yet she has known when to step back and recharge. She took six months out in 2018, immediately after completing On Chesil Beach - another McEwan adaptation.
In interviews, she has suggested that the struggles of her parents to make it in their chosen fields (her mother Monica also acted when younger) has helped to not just drive her forward, but to ensure that complacency doesn't set in.
"They had to struggle for a long time," she has said. "Ma watched dad lose out on parts or star in shows off-off-Broadway and make buttons. I watched these really talented people never get the shot they deserved.
"So, they prepared me to be realistic. And that's good, because the moment fame becomes a priority, you should give it up."
Her parents have been supportive of her daughter's acting work from day one, especially when it came to school.
When Ronan began to feel that she was getting a hard time in the classroom, her parents opted for home-schooling instead.
"Some of the students were, you know, mean," she said recently. "But when your schoolmates recognise you before they've met you, and the teachers do too, it can make things very awkward and difficult."
Ronan has been hailed as one of the greatest screen stars of her generation; fellow Irish actor Colin Farrell has suggested that she "doesn't have a dishonest bone in her body and that translates into her work on the screen".
According to The Observer, her career choices have been impeccable.
"With the exception of this little pop outing (in the video for Ed Sheeran's Galway Girl) and, perhaps, her cameo in Muppets: Most Wanted, the actor is distinguished by a succession of rather sober career choices. She has taken risks with sophisticated screenplays, instead of opting for obvious crowd-pleasers."
She has also succeeded on the stage. In 2016, she won praise from critics for her performance in a Broadway production of Arthur Miller's The Crucible.
Today, Ronan divides her time between New York - where she has a home - and Ireland, but the nomadic life of a major film star means she is often away for months at a time.
Ever busy, she has recently completed a pair of films, which will be released later this year.
The French Dispatch, directed by Wes Anderson, will see her team up with Lady Bird and Little Women co-star Timothee Chalamet once more, while in period drama Ammonite she performs alongside Kate Winslet and fellow Irishwoman Fiona Shaw.