Florence Pugh in The Wonder

LONDON 鈥 Making her new psychological period thriller The Wonder was a lesson in reining in her spirit and holding her tongue, British star Florence Pugh says.

Ms. Pugh plays English nurse Lib who travels to a remote Irish village in 1862 to 鈥渨atch鈥 a young fasting girl.

Lib and a nun have been hired to take turns to observe the 11-year-old, who claims to not have eaten for four months, surviving on 鈥渕anna from heaven.鈥 They are to present their findings to a committee of local men after two weeks.

With the healthy girl regarded a religious wonder and fast becoming a local celebrity, Lib sets out to discover the truth behind her claims, much to the disapproval of many in the community.

鈥淔or me it鈥檚 a conversation and a conflict about science versus religion, something that we鈥檙e dealing with now, something that… it鈥檚 a tale literally as old as time,鈥 Ms. Pugh told Reuters at the movie鈥檚 London Film Festival premiere on Friday.

鈥淲e have a strong, stubborn woman who knows that she is right in certain aspects, unable to talk her truth… So to me, it was more about biting my own tongue and all the films that I know, I love doing, is me getting in there and going in guns blazing and I couldn鈥檛 in this one because ultimately at that time it wouldn鈥檛 happen.鈥

Based on a novel of the same name by Room writer Emma Donoghue, The Wonder opens with a behind-the-scenes look of the film set, with a voice-over inviting audiences to believe in the story.聽

鈥淚t鈥檚 just a little framing so people can be aware that they are being exposed to the power of fiction, which is exactly what the film is about, the stories the characters are trapped in, or the stories they choose so they can reach new levels of freedom,鈥 the film鈥檚 director, Chilean filmmaker Sebastian Lelio, said.

Ms. Pugh鈥檚 grandmother Pat, who made her red-carpet debut as Ms. Pugh鈥檚 date for the Don鈥檛 Worry Darling world premiere in Venice last month, accompanied her again on Friday.

鈥淪he鈥檚 literally living this sparkly dream. She didn鈥檛 get to do this before and she loves it. I mean, she was on the sidelines, like, let me come!鈥 Ms. Pugh said.

The Wonder launches on Netflix on Nov. 16. 鈥 Reuters