Amanda Seyfried's character, Catherine, in the new Netflix supernatural thriller, "Things Heard & Seen," not only must confront spirits occupying her upstate New York home but also dark secrets within her marriage. 

The Oscar-nominated actress revealed playing someone who is going through such personal turmoil was "exhausting."

"It is intense... a lot of the physical [stunts] that I have to do. But in terms of [emotions], it's a little exhausting but the truth is I know every part of this character," she explained to Fox News while promoting the film. 

"It's one of the reasons I was attracted to the movie and to tell the story is because there was such an arc and it happened over the course of a couple of months. You get to explore all these different facets of this one woman in this marriage that's terrifying," Seyfried added.

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Her on-screen husband, James Norton, confirmed he did deep background preparation to play such a manipulative spouse. 

"It was important because obviously [the character's past] was obviously contributing to his unraveling and he was on this journey of self-destruction from a much earlier age," the British actor explained. "So it was important to tap into that."

This image released by Netflix shows James Norton (L) and Amanda Seyfried (R) in a scene from 'Things Heard & Seen.' (Anna Kooris/Netflix via AP, File)

The film, directed by Shari Springer Berman and Robert Pulcini, took place in the Hudson Valley, where Seyfried lives with her husband and two small children. 

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She said she loves the "energy" upstate. "That's where I live, it's where I will die, it's so rich with nature and just everything. I can't get enough of it and being able to shoot [the film during] the most beautiful time of year just added to the whole [experience]. [Hudson Valley] is a character in itself in this movie."

Springer Berman told Fox News that adapting the script from the book by the same name was a time-consuming and tedious process.

Amanda Seyfried said filming in upstate New York was amazing because of the rich nature.  (Anna Kooris/Netflix via AP, File)

"I didn't immediately know [what I would keep from the book]. It was a process because the book is quite epic. And we really needed a limited series to fulfill the book. So it was a process of writing drafts, trying to know what you're going to include, what you're not going to include, and then reading it back and then redrafting. So it was a fairly long adaptation process to just find the right material," she described.

Springer Berman said she was inspired by '70s classics such "Rosemary's Baby" or "Don't Look Now" or even the movie, "What Lies Beneath."

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She felt the stories are appealing because they're about "real relationships, real people, real emotions. And the supernatural element is just sort of layered on top of it."

"Things Seen & Heard" is available to stream Friday on Netflix. 

FOX's Ashley Dvorkin contributed to this report.