Jessica Chastain and Eddie Redmayne's new Netflix film "Good Nurse" tells the true story of serial killer Charles Cullen, an ICU nurse who admitted to killing 29 of his patients but may have murdered more than 300.

Based on Charles Graeber’s 2013 book, "The Good Nurse: A True Story of Medicine, Madness and Murder," the movie centers on Cullen's fellow nurse and friend Amy Loughren (Chastain), who exposes his crimes and brings an end to his killing spree.

Director Tobias Lindholm and screenwriter Krysty Wilson-Cairns told the Associated Press that they made a deliberate choice to focus the story on Loughren and the failures within the U.S. healthcare system that enabled Cullen to murder his victims for 16 years.

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Jessica Chastain and Eddie Redmayne's new Netflix film "Good Nurse" tells the true story of serial killer Charles Cullen. ((Photo by Dia Dipasupil/Getty Images)

"I saw the potential of doing a serial killer in a way that we had never seen it before, where we wouldn’t be seduced by why is he doing this or how damaged is he as a person, but take a step back and look at why and how would we allow for this to go on," Lindholm said. 

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"He’s not, in my mind, Hannibal Lecter. It’s not this brilliant mind. It’s a fairly simple guy doing a fairly simple thing, but a system allowing it.

Cullen used his position as a nurse to kill his patients by injecting their IV bags with lethal doses of medications. He was able to evade detection by transferring from hospital to hospital in New Jersey and Pennsylvania. Both the book and the film suggest that for-profit hospitals covered up for Cullen in order to avoid potential liability.

"This case asks us if it’s a good idea that people are making money from other people’s health," Lindholm said. "Is it a good idea that hospitals are businesses?"

Wilson-Cairns starting writing her adaptation of Graeber's book 10 years ago. She told the AP that she began her research by visiting Loughren at her home.

"I turned up at the real Amy’s house in upstate New York," Wilson-Cairns recalled. "I think I was 23 or 24. I was like: ‘I’ve never done this before. It’s really important to me. It’s your life story. Can you help me?’"

In addition, Wilson-Cairns shadowed nurses for two weeks at a hospital in Connecticut. "What I found is that the actual health care providers — the doctors, the nurses, the radiologists, the anesthesiologists — all these people are incredible and are heroic," she said. 

"They put their lives in a box so they can help save other people. I don’t think any of them are paid enough. I think even at 10 times, those nurses aren’t paid enough. I learned that the system they are forced to work within is not the best for patient care."

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 Cullen was sentenced to 11 consecutive life sentences in 2006. (John Wheeler/Getty Images)

Chastain took inspiration for her portrayal of Loughren from her conversations with the real-life nurse. In order to depict Loughren's arrhythmia realistically on screen, Chastain jogged around to get her heart rate up before filming. She also wore an ear piece with a heart beat that could accelerate while she was shooting a scene.

"She worked nights so her daughters felt like she was a stay-at-home mom. That’s what she kept saying, that her kids saw her when they were awake," Chastain said. 

"The idea that this woman would risk her health in order to provide for her children and also risk her comfort by not getting the sleep she needed, it told me so much about who she was and what she was capable of."

Redmayne, who played Cullen, watched footage of the real-life Cullen from his court appearances and his 2013 interview on "60 Minutes". Cullen was sentenced to 11 consecutive life sentences in 2006.

"There was something in his physicality that was interesting to me," Redmayne said. "He’s a very still man. But if you actually look close, you’ll see he’s always soothing himself. I don’t know if soothing is the right word, but touching fabrics. 

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"Good Nurse" premiered at the Toronto International Film Festival on Sept. 11. (Photo by Taylor Hill/FilmMagic)

"There’s always something moving. The guy was a horrendously damaged human being and that idea of looking for comfort was interesting to me."

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"Good Nurse" premiered at the Toronto International Film Festival on Sept. 11 and Loughren received a standing ovation when she took the stage. Wilson-Cairns said that she was particularly moved to see Loughren celebrated for her heroism. 

"This woman just wasn’t recognized for what she did," Wilson-Cairn said. "People don’t think of ordinary women as these kind of heroes. They’re not on screens, they’re not in the media, they’re not in books enough. 

To see the real Amy finally be recognized in a small way for what she did – which is save countless lives – I thought: That’s not a bad way to spend a decade. I’d do that again."

"Good Nurse" will begin streaming on Netflix on Oct. 26.

The Associated Press contributed to this report.

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