Zac Efron portrays Ted Bundy, one of the most prolific serial killers of all time, in Extremely Wicked, Shockingly Evil and Vile. Georgia Humphreys chats to the actor, his co-star Lily Collins, and director Joe Berlinger about their experience of bringing the horrifying story to life.
There have been various opportunities for Zac Efron to take a darker turn as an actor. But the former Disney star, who became a teen heartthrob around the world thanks to the High School Musical franchise, has always been hesitant, to make sure it's the right sort of role.
"More often than not, they're something I'm not necessarily interested in lending my image to and they do seem like glorifying somebody, that we're telling a random story for no purpose," notes the affable 31-year-old, who was born in California.
That's why he had reservations at first about playing Ted Bundy, one of America's most notorious serial killers, in Extremely Wicked, Shockingly Evil and Vile, based on the non-fiction memoir by Elizabeth Kendall - the pseudonym Liz Kloepfer, who was Bundy's long-term girlfriend, used when she penned the book.
But after talking it through with director Joe Berlinger, who also made the recent Netflix documentary series Conversations With A Killer: The Ted Bundy Tapes, he changed his mind.
"This isn't the procedural 'evil guy, body count stacking up and then he gets caught and now you know about that person, how bad they were'," explains Efron, whose other film credits include Baywatch, The Greatest Showman and Hairspray.
For Oscar-nominated filmmaker Berlinger, the casting of someone like Efron was purposeful, because "to a certain segment of the population" he is "a guy who can do no wrong".
"I want the audience to have the same experience as the people who trusted Bundy, and part of that experience is actually rooting for Ted for the first part of the movie," adds the 57-year-old American.
The story follows single mother Liz, played brilliantly by Lily Collins, as she meets Ted on a night out, and thinks she's found the man of her dreams.
They move in together, becoming a family unit along with her daughter from a previous relationship, Molly.
A few years later, he's arrested on suspicion of kidnapping, before being linked to murders in multiple states - but Liz refuses to believe Ted is guilty for a long time.
A former law student, he insists he's been framed and chooses to defend himself in America's first nationally televised trial, while, as time goes on, Liz starts to question what she believes.
Discussing her character, Collins, 30, suggests: "She only knew the man that she was faced with, and that was a man that, to her, loved her, loved her child.
"He was supportive of her, she was supportive of him and she has never seen this other side - this 'so-called' side, because she didn't believe it to be true.
"She wasn't privy to any of the imagery and what's really going on, the court cases - until they were televised she wouldn't have seen anything," continues the actress, known for her role in BBC series Les Miserables, and who stars in the upcoming film Tolkien, also released in May.
"So, playing that part at the beginning, as well as at the very end, was an interesting character arc for me, or for any actress, to come in and play, because there are so many different levels that she goes through in this story."
It was just days before he was executed in Florida on January 24, 1989, that Bundy finally confessed to murdering over 30 women between 1974 and 1978 (though experts believe the true number of his victims is much higher).
A question the film raises is whether Ted, who used his good looks and charm to lure his victims to their death, actually ever loved Liz.
As Efron puts it: "Is a sociopath or a psychopath capable of love?"
What does Collins think?
"I met with Liz and her daughter Molly and I think it's my understanding they felt love there..." responds the star, who is the daughter of musician Phil Collins, and was born in the Surrey but moved to LA with her mum when she was a child.
"She showed me hand-written love letters from him to her, that were so powerful, written on actual paper, so deeply written that it was embossed in there, and you could feel energy, you could feel love, you could feel whatever emotion it was that you were feeling, it was there.
"I find it difficult to believe that that type of thing could be written without emotion. And I feel there was a lot of love there; I don't know what kind of love it was, or what level of love, but it was there."
"Or a sense of comfortability, or a sense of three-dimensional love - maybe that was what he was creating," Efron chimes in.
"To a certain extent I'm sure a part of him wanted that."
What's undeniable is how captivating the stars are in their wholly believable performances.
Meanwhile, Berlinger defies the idea the film sexualises Ted Bundy, reasoning people who say that don't know the story.
"He was a person who had women showing up at the Florida trial thinking he was innocent, or even if they thought he was guilty, they were so titillated by him that they wanted to be in the same room," he says.
"So we are not sexualising the serial killer, we are telling the story of what really happened in real life."
Both the filmmaker and his cast knew the movie had a very important message - one that can't be overstated, especially to the younger generation.
"Just because somebody looks and acts a certain way, it doesn't mean you should just implicitly trust them," elaborates Berlinger.
"In this era of internet catfishing, and people on social media pretending to be one thing when they're in fact another, that's a lesson that I want my daughters, who are college-age women, who didn't know who Bundy was when I started this project... That's a lesson I want young people to know, that you have to be really careful.
"Whether it's the 1970s or today, there are people who pretend to be one thing and really are another."
Extremely Wicked, Shockingly Evil and Vile is released in cinemas and on Sky Cinema on Friday, May 3