The Anne Frank Centre recently declared The Zookeeper’s Wife “one of the most essential movies on the Holocaust we’ve seen”. Telling the remarkable story of Antonina Żabiński and her husband Jan, keepers at the Warsaw Zoo who hid more than 300 Jews during the Second World War at great personal risk, it is certainly a powerful reminder of the horrors and humanity that went hand-in-hand during this time.

Playing Antonina is American actress Jessica Chastain (Zero Dark Thirty), who feels it’s not just a story about the past. “It’s so timely, with everything that’s happening — very, very timely.

“It’s basically about refugees.”

She’s referring, in part, to her own character. “She was born in St Petersburg and her father was killed in Russia, and then she fled and ended up in Warsaw.”

Starring alongside the Flanders-born actor Johan Heldenbergh (The Broken Circle Breakdown), who plays her husband, Chastain was immediately hooked when she read the script by Angela Workman, adapted from Diane Ackerman’s book, itself inspired by Antonina’s diaries.

“It’s an incredible story,” says Chastain, “and most people didn’t know about it until her journals were found.”

With the couple smuggling Jewish families from the ghettos and hiding them in the basement of the zoo, the task is made all the more difficult by the attentions of Hitler’s zoologist, Lutz Heck, played by Daniel Brühl.

“He was this talented, passionate zoologist,” says the German actor, “starting off as a friend and colleague of this couple, and then becoming absorbed by this horrible Nazi ideology and slowly becoming an animal and a monster himself.”

For Chastain, the project was more than just another acting role. Serving also as an executive producer— just her second such credit, after 2014’s The Disappearance of Eleanor Rigby — the 40-year-old sees it as part of her evolution as an actress. With her own production outfit Freckle Films now in operation, she’s keen to bring stories like The Zookeeper’s Wife to life. “I want to create more stories with diversity.”

Unusually, the film boasts a female director (Whale Rider’s Niki Caro), producers, screenwriter and other key crew members.

“It was very strange to have so many women on set,” says Chastain. “And it was wonderful. Also the guys loved it! That’s why I don’t understand [about] movies [where] it’s mostly men. On the site, everyone was so happy. The guys were so happy because there were more women around. The women were happy because there were girls to talk to.”

The Zookeeper’s Wife opens on April 21st.