The Wicklow born actress will play the lead as Rona, a recovering alcoholic, who after leaving rehab returns to the Scottish Island where she grew up.
There she "reconnects with the dramatic landscape where she grew up."
While there she begins to piece together her childhood, memories of it “merge with the more recent challenging events that have set her on the path to recovery.”
The film will be directed by Nora Fingscheidt and was written by Fingscheidt and Liptrot, with 27-year-old Ronan as an executive producer. Her boyfriend Jack Lowden will also be a producer for the flick.
Speaking about the upcoming movie, Saoirse said it was Amy’s voice that first drew her to the story.
“Her unusual way of seeing things in a way that perhaps you only can when you’ve been to the darkest place you can go within yourself,” she said.
“I have been waiting to play a part like this, the messiness, hopefulness, dreaminess, authenticity and humour we want to achieve, I’ve been scared of it, but with Nora I feel ready.”
Fingscheidt added: “There are wonderful gifts already in place to make this a powerful and immersive film.”
“One is the setting, the vast and cinematic landscapes of the Orkney islands. The other is our main actress, Saoirse Ronan, who brings magic to the screen with her unique mix of charisma and emotional depth.”
Janina Vilsmaier, of Protagonist Pictures, said: “Nora, with her mesmerising filmmaking style, and Saoirse, with her endless skill and bravery are the perfect team to bring Amy’s award-winning memoir to screen.”
“The Outrun will be an incredibly cinematic and powerful film, which will offer us a glimpse into the life of this amazing young woman, transporting us on an emotional and ultimately life affirming journey.”
Last year, Saoirse Ronan wrapped up filming her upcoming flick
See How They Run, in which she stars as the lead Constable Stalker.
She is currently filming ‘Foe’ in Australia in which she stars alongside Paul Mescal.