Jessica Chastain, Eddie Redmayne tell serial killer story in 'The Good Nurse'

Based on a book of the same name, "The Good Nurse" centres around ICU nurse Amy Loughren who in 2003 helped uncover the murders committed by her colleague and friend Charles Cullen.

Oscar-winner Jessica Chastain plays Loughren, a single mother and cardiomyopathy sufferer who pulls long night shifts in a New Jersey hospital in order to qualify for health insurance.

Struggling with the workload, she is relieved when the seemingly highly qualified Cullen, played by fellow Academy Award-winner Eddie Redmayne, is hired to work with her. The two quickly form a bond and Cullen helps Loughren cover up her illness and care for her two young daughters.

Following the sudden death of two patients in the ICU detectives become suspicious of Cullen and his past employment in other hospitals. To catch him, they need Loughren's help.

"It was very stressful because I'm playing a real person. I need to honour what she did, her heroic acts but then I also need to make sure it's not sensationalised and fetishised for consumption. And so it felt like a big responsibility," Chastain told Reuters at the movie's London Film Festival premiere on Monday.

“The Good Nurse” is directed by Tobias Lindholm, writer of the Oscar-winning Danish film "Another Round", making his English-language feature debut.

Cullen, who confessed to killing up to 40 patients, was sentenced to 11 life terms. Investigators believe the real number of patients he murdered could be up to 400.

"Meeting the real Amy Loughren, who talked about how this person was a close friend of hers, someone she loved, someone she found funny and empathetic, and that she only ever met this murderer, this killer, twice and it was a different human being. That was a kind of insight," said Redmayne of playing Cullen.

Loughren, who retired a year and a half ago, travelled to London for the film's premiere.

“It’s such a hard subject matter that I really struggled with being OK with being excited. And I didn't want to sensationalise a serial killer,” she said.

“I'm so proud of what Tobias did with this story, that I can celebrate his art. I can celebrate Eddie working so hard at his craft. I can celebrate who Jessica is and that she played the me from 20 years ago. It's wonderful. I'm honoured."