Saoirse Ronan is having quite the season.

A four-time Oscar nominee, Ronan’s virtually one-woman rehab drama “The Outrun” has put her in the Best Actress Oscar race. While “Blitz,” Steve McQueen’s acclaimed WWII homefront drama, has her a likely Best Supporting Actress nominee.

The Irish actress, 30, had planned on taking a six-month break when McQueen paged her to star in his harrowing portrait of 1940 London.  The “blitz” saw waves of German bombers target London civilians, bombarding the capital nightly. A million children were evacuated to the countryside for safety.

Ronan’s Rita, a single mother with biracial 9-year-old son George (newcomer Elliott Heffernan, 9 when he filmed), packs him off to live with strangers. However, an unhappy, furious George leaps from the moving train. “Blitz” then charts his determined journey home.

“I wanted,” McQueen said in a joint virtual press conference with his star, “to look at the domestic situation when the women became the pillars that kept the nation going.”

“I felt this was something that would be fresh, grounded in reality. And I wasn’t wrong,” Ronan noted. “We did a lot of research in the period of time of course.

“It was during prep that I built a lot of the intricacies of the dynamic between mother and child from my own relationship with my mom. I was inspired by that.

“We also got to work on these mini-projects before filming started, like recording music written for us at Abbey Road studios.”

Key to the success of “Blitz” is the mother-son connection. “There was chemistry from Day 1,” McQueen marveled. “She took him under her wing. That was reciprocated and this affection grew and grew.”

Heffernan, discovered from an open casting on Facebook, was remarkably adept and capable from the start.

“It’s very unusual to work with a 9 year old who is available and able to improvise,” Ronan knows being a child actor herself. “Who is open to make believe but also confident enough to spar with actors who have been doing it a long time.

“Because he had that from the very beginning, it felt like we were working with a fellow actor. It didn’t feel like we were holding his hand.

“Because of that beautiful youth,” she added, “you can totally believe in something in an unembarrassed way. And that reminded us of how we were when we began as a young actor.”

An amazing footnote: “Our makeup designer Naomi  Donne said Hitler hated women wearing red lipstick. So it was strongly encouraged in the UK and America to wear it. It was made in pocket size so girls could do this act of defiance.

“I found that to be absolutely incredible.”

Apple TV+ streams “Blitz” Nov. 22