Bringing true stories to the screen can be a tough balancing act between respecting the real people involved and crafting a compelling story from facts and first-person accounts. Beautiful Boy, from Belgian director Felix van Groeningen, tells the true story of the Sheff family, focusing particularly on the relationship between father David (Steve Carell) and son Nick (Timothee Chalamet), who spirals further and further into drug addiction throughout his adolescence and twenties.

Beautiful Boy differs from a lot of other film adaptations because of its source material – or source materials. The film is based on the books of both David and Nick Sheff, offering dual perspectives on one family’s immense struggle through addiction.

The director tells Den of Geek: “I really fell in love with the idea of combining two books, two points of view. I think there’s something really unique in that. The subject matter is something I’ve dealt with in previous films, and something I’m fascinated and intrigued by, but never in this way. When I read both books it was really an eye-opener for me in that I could really feel how hard it was and understand more than ever how addiction is not a choice.

“Seeing the impact on the family, I thought it was so heartbreaking and moving at the same time. For the fact that it’s a true story, which doesn’t shy away from dark moments but is also inspiring for being the story of family somehow getting through it. It doesn’t say there are easy answers when it comes to addiction.”

The film couldn’t have been made the way Groeningen wanted without the input of the two authors, he says, and it was a blessing for David and Nick to welcome the crew into their worlds.

“I met them very early on and it was about just getting to know each other and feeling each other out,” he says. “I ultimately fell in love with the Sheff family in the books and when I met them I found the same warm and inspiring people.

“Once they knew I wasn’t going to turn it into a typical Hollywood story, there was a lot of talk and they had a very hands-on approach. They were there and open to me asking questions… Their openness and their allowing me into their lives was ultimately very important to the film. The look and feel of it, but also its heart.”

The adaptation process was less than simple, with Goeningen and co-writer Luke Davies having to incorporate both points of view while also constructing a powerful narrative of their own.

“We took our time boiling down the two books,” the director explains. “Adapting one book is very difficult, but two books is a lot. There’s a lot to choose from and a lot of great material, very gripping and moving scenes. How do you find the thread between them and how do you let the characters evolve while also embracing the fact that they’re in this repetitive cycle that comes with addiction? I wanted to embrace that, and it was important to make it authentic and raw, to make it real.”

This posed some structural questions, which ultimately resulted in a slightly non-linear telling of the Sheff family’s past and present. As we travel through the ups and downs of Nick’s addiction, we also see glimpses of his past, and the warning signs that may have been missed.

“I always knew we were going to need flashbacks in order to make it work. David and Nick’s books are both very different, so the movie is something else. The movie takes a couple of years where they discover they’re really in the midst of it and David is realising he’s losing his son, and he’s questioning how he got there or what he could have done better. But he’s also remembering beautiful moments.

“The thing that changes from script to final film is that we played differently with that. It doesn’t feel this way [when watching] but the movie is actually very linear. We go from one rehab to the second rehab to college. What is less linear is how the flashbacks play in between. In the script, it was a little more cerebral and we wanted to really find the emotional logic of the movie. So we restructured thing and let it work the way memory works.”

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Of course, that fact that star Timothee Chalamet has hit what the director calls “Beatles stardom” in the time between the film’s production and release can’t hurt its performance, and Groeningen was blown away by the diversity in audiences he witnessed.

“What is really remarkable and what we’re really proud of is that this film works for a lot of different people,” he said. “Young people want to see it with their parents, and parents want to see it with their kids. It was part of why we wanted to make this film, so we can have conversations about being young and growing up.”

Beautiful Boy is in UK cinemas from 18 January