Jodie Comer says working with 15 different babies on the set of her latest film - disaster movie The End We Start From - was both "beautiful" and "challenging".
The 30-year-old Killing Eve star plays a nameless woman, giving birth to her first child just as apocalyptic floods hit London.
She told Sky News: "The babies are allowed on set for 20 minutes and then they have to go, so you're often having to adapt to that.
"Sometimes you could be in a very honest moment with the baby, you know, the baby's giving you something that makes you react in a certain way, and then you have to try and recreate that with a doll - it's difficult.
"And sometimes the kind of terrain we were working on when we were filming in Scotland, you can't have the baby, or if you were in a boat.
"So, there are lots of different kinds of challenges along the way. But I think some of the most beautiful moments that we have [in the film] are when we see baby on screen and seeing the world through his eyes and his reactions."
To perfect her parenting skills, director Mahalia Belo gave Comer some homework.
"I took a doll home and Mahalia said to me, 'Look, I want you to carry the baby, and I want you to put the washing on and make a cup of tea and just get used to having this little person attached to you 24/7, to get used to what that feels like and the physicality."
On her part, while Belo wanted her lead star to be a convincing new mum, she didn't expect Comer to achieve "Bear Grylls" levels of survival techniques for the shoot.
She says it was more about showing her heroine's developing resilience as she fights to survive with her newborn son, sometimes turning to nature to get by.
'Acting on instinct'
Belo says those moments of connection and desperation were about seeing a woman "falling out of her character" and "step that little part further than she would normally go".
Comer agrees: "It came from her primal instinct to keep her son safe. It felt like it was always coming from that place of 'As long as baby's as clean as possible, safe, and fed', then that was the first and foremost thing."
Talking about a moment when a woman takes extreme action to get where she needs to be, she says: "It felt very real. You could see that she was totally desperate in the way in which she did it, on such an impulse.
"There was nothing fancy about it. There were no stunts. It was just instinct and acting on it, and I think that's what she's doing throughout the movie."
The writer of the book the movie's based on, Megan Hunter, tells Sky News she never saw it as a film.
'A brilliant team of women'
Written as what she describes as a "prose poem", Hunter was swiftly proved wrong when the rights were snapped up by Benedict Cumberbatch's production company, SunnyMarch, before the book was even published.
Modestly, she credits the "brilliant team of women" behind the film - director Belo, Alice Birch who wrote the screenplay, cinematographer Suzy Labelle and of course the film's star, Comer, and co-star Katherine Waterston for "creating something so beautiful".
Hunter says while the film's faithful to the novel, it also stands as "a work of art in its own right".
See more of our interview with Jodie Comer and director Mahalia Below on The Climate Show, Saturday at 3.45pm.
The End We Start From is in UK cinemas now.