When Christopher Nolan cast Harry Styles in his new World War II thriller Dunkirk, he had no idea he would spark a social media storm. "I don't think I was that aware of how famous Harry was," he admits. "I mean, my daughter had talked about him, but I wasn't really that aware of it. So the truth is, I cast Harry because he fit the part wonderfully and truly earned a seat at the table."

Harry Styles stars in DunkirkHarry Styles stars in Dunkirk

This is Styles' acting debut, as part of an ensemble that includes Tom Hardy, Mark Rylance and Kenneth Branagh. And he admits that he had no idea what to expect on the set. "It was amazing," he laughs. "The first surprising thing was the scale of the production. You walk on set the first day and get taken aback by everything. The movie is so ambitious! Some of the stuff they're doing in this movie is insane. I think whatever you imagine a giant film set to be like, this was very ambitious even by those standards. You know, the boats and the planes and the volume of bodies!"

As for acting, he found it a challenge both physically and personally. "I loved being so far out of my comfort zone," he says. "I love acting, I love playing someone else. It was hard, physically really tough. But I really loved being the new guy. It felt really good to kind of have no idea what I was doing for a little bit."

Styles says that it helped that there isn't much dialogue in the movie, and that Nolan's style of writing and directing encouraged him to become the character. "I think Chris kind of creates this world around you where you don't have to act too much," Styles says. "A lot of it is reacting. I think as much as anyone could possibly help you be in a situation, he creates that for you. He asks you to just say what you need to say and don't try to overthink it. But I think the thing with Chris' script is the same across a lot of his other movies, which lend themselves to multiple viewings. I feel like you learn new things each time you watch it."

And Styles admits that he might have the acting bug. "It was one of the best experiences of my life," he says. "I think being on a set like this it's hard not to be always learning. Being around people that you're a fan of just feels like a privilege! Soak up as much of that as possible."

Watch the trailer for Dunkirk: