Alexander Skarsgard, who plays Bosworth's old boyfriend, had the challenge of making his character more than just the "bad guy."
"This was a great opportunity to do something different and something new," he said. "To play a guy who's on the paper the villain, but to kind of make him real and human, and also try to get the audience to kind of at least in the first half of the movie almost like the guy, or at least understand the guy, and maybe be on the fence whether she should go back to her ex-boyfriend or not."
The film is intense, with a strong R rating from the MPAA for brutal violence.
"These scenes were so intense, psychologically, in the parlor games between my character and Alexander's character and obviously the intensity of the violence towards the end of the movie. It got to me a bit, I must say, there was a lingering effect," said Marsden.
But when the cameras weren't rolling, the cast made a point of keeping things loose.
"There was a lot of hanging out, I think we all needed a beer or two after a day's work on this movie," said Marsden.
"When you work on a movie like this, it's just, to me at least, important to on weekends or days off to just go out and have a good time together. And so you kind of balance it out a bit because then you dive back into, straight down the rabbit hole on Monday morning, said Skarsgard.
"Straw Dogs" opens in theaters Friday, Sept. 16.