Kerry Hayes/20th Century Studios Bradley Cooper in Nightmare Alley
Bradley Cooper is opening up about stripping down.
The Nightmare Alley actor has a full-frontal scene in the new Guillermo del Toro-directed psychological thriller, and recently chatted with The Hollywood Reporter editor-at-large Kim Masters about doing the "big deal" scene on her KCRW podcast The Business.
"I remember reading in the script and thinking, 'He's a pickled punk in that bathtub and it's to story. You have to do it,' " Cooper, 47, told Masters of his character, Stanton Carlisle.
The scene went down during Toni Collette's "first day" of filming — and Cooper was required to be nude "in front of the crew for six hours."
"It was just like, 'Whoa.' It was pretty heavy," said the eight-time Academy Award nominee.
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human-interest stories.
Kerry Hayes/20th Century Studios Bradley Cooper and Toni Collette in Nightmare Alley
Set in the 1940s, the dark and twisted plot of Nightmare Alley, based on William Lindsay Gresham's 1946 novel of the same name, follows the wild ride of Carlisle, an ambitious carny-turned-mentalist who discovers a knack for sleight of hand and showmanship and begins a journey into a bigger city as a master manipulator.
Benefiting from the exploitation of his conned clients, he finds himself desperate to escape his own dark fate as he plots to fool a dangerous tycoon with a mysterious psychiatrist (Cate Blanchett) by his side – who might be his most threatening opponent yet.
When he read the script, Cooper told Masters, he wasn't fazed by the nudity requirement "because there was nothing gratuitous about it. It was to story."
"The content of what the movie is, what we were exploring, in order to do it in a real way, it demanded that we'd be naked emotionally and soulfully," he also said.
RELATED VIDEO: Industry's Myha'la Herrold Was "Stoked" About Show's Nudity: "Sex Is Not Used as Shock Factor"
Cooper previously told Deadline that his Nightmare Alley role (which marks his first completely nude scene) "terrified me, for many reasons."
"But as we started to delve into it — and we had the real benefit of time and prep to work on this — the idea of inhabiting somebody who doesn't know who they are, and who's in search of who they are through the whole film, right up until the last scene," he explained. "I thought, 'Maybe that's where I am in my life as an actor and a human being.' "
Cooper continued, "It was important to go there, unflinchingly and boldly, which I was able to do with Guillermo hand-in-hand. It cost something for us emotionally, making this movie. It was very risky to go to these places of, 'Are we this person? Is this a side of ourselves? Is this who we really are?' "
"I found that to be quite vulnerable as an actor," he added. "All my characters tend to linger, but this one, I have to say, was an especially hard one."
Nightmare Alley is in theaters now.