Jamie Dornan told Elle UK that he visited a sex dungeon to prepare for his role as an S&M-loving billionaire in the Fifty Shades of Grey movie Credit: Phillip Massey/WireImage

It's a dirty job, but somebody's gotta do it. Jamie Dornan didn't just walk onto the Fifty Shades of Grey set and start acting — he did his research first. Prior to taking on the role of S&M-loving billionaire Christian Grey in the film adaptation of E L James' wildly popular erotic novel, he paid a visit to a "sex dungeon" for a little lesson in kink.

"I went there, they offered me a beer, and they did...whatever they were into. I saw a dominant with one of his two submissives," the Once Upon a Time hunk, 32, told Elle UK for its February issue, which hits stands on Jan. 2.

"I was like: 'Come on, guys, I know I'm not paying for this, but I am expecting a show,'" he quipped to the mag. "It was an interesting evening. Then going back to my wife and newborn baby afterwards...I had a long shower before touching either of them."

(The Irish-born actor and wife Amelia Warner welcomed their first child, a daughter, in November 2013.) 

The sex dungeon wasn't Dornan's only preparation, though. As he revealed to The Guardian earlier this year, he became quite adept at working with his hands. "There are a couple of classic knots I know now, and I've put them to good use far too many times recently," he said in April. "In fact, I'd like to do a job where I don't have to tie women to beds." 

Fifty Shades of Grey, which stars Dakota Johnson as Anastasia Steele, is due to hit theaters on Valentine's Day 2015.