Actor Eddie Redmayne got candid about his experience attending nursing school to prepare for his role in the upcoming serial killer film "The Good Nurse."

The actor, who portrays real-life serial killer Charles Cullen – an ICU nurse who admitted to killing 29 of his patients – spent two weeks at a nursing school learning about what nurses do.

'I was totally s--- at it, you never want me in a crisis," Redmayne joked to British GQ. "I have no grand plan, I'm just winging it."

Based on Charles Graeber’s 2013 book, "The Good Nurse: A True Story of Medicine, Madness and Murder," the movie revolves around Cullen's fellow nurse and friend Amy Loughren – played by Jessica Chastain – who exposes his crimes.

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In addition to attending nursing school, Redmayne also watched footage of the real-life Cullen from his court appearances and his 2013 "60 Minutes" interview.

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Eddie Redmayne and Jessica Chastain star in "The Good Nurse." (Dia Dipasupil/Getty Images)

"There was something in his physicality that was interesting to me," Redmayne told The Associated Press. "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. 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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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.

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Jessica Chastain portrays Amy Loughren, while Eddie Redmayne portrays serial killer Charles Cullen. (Taylor Hill/FilmMagic)

Cullen was sentenced to 11 consecutive life sentences in 2006.

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Eddie Redmayne attended nursing school to prepare for his role in "The Good Nurse." (Karwai Tang/WireImage via Getty Images)

"The Good Nurse" will stream on Netflix beginning Oct. 26.

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