• Cary Elwes starred in Rob Reiner's 1987 movie "The Princess Bride."
• Elwes last worked with the director on Reiner's 2016 movie "Being Charlie."
• Reiner's son, Nick, wrote the screenplay about his struggles with drugs and mental health.

Cary Elwes will always be indebted to Rob Reiner for giving him his big break in show business, casting the then-unknown British actor in the lead role of his beloved 1987 movie "The Princess Bride."

So when Reiner called Elwes 29 years later to ask him to be part of the most personal project of the filmmaker's career, the actor was more than willing to oblige.

"He told me that I would be playing a character who is very similar to him because he wanted to explore the family dynamic of having a child who was having mental issues," Elwes told Business Insider of his role in the 2016 indie film "Being Charlie." Elwes said he "jumped at the opportunity" to work with Reiner again.

"Being Charlie" was written by Reiner's son, Nick, who, after struggling with drug addiction for years and being in and out of rehab, decided to write a screenplay about the experience and asked his father to direct it. The movie stars Nick Robinson in the lead role as a young man struggling with drug addiction and his mental health. Elwes plays his actor-turned-politician father.

"It forced me to really have to understand what he had been going through for a long time," Rob Reiner told Business Insider back in 2016 about making the movie with his son.

The film would return to the zeitgeist in December 2025 when Nick was arrested in connection to the murder of his parents. His trial is scheduled for September; he has pleaded not guilty.

"It's bittersweet that that's the last thing we worked on," Elwes said, reflecting on his friendship with Rob Reiner. "But I tend to want to remember him for the wonderful contributions that he gave to our industry and to the people who loved him, rather than focus on anything negative. I don't want to focus on how he died, I want to celebrate how he lived."

Despite the stigma that hangs over "Being Charlie," Elwes, who currently is starring in the Peacock series "M.I.A," believes the movie still delivers a powerful message about addiction and seeking help.

"If Rob would want anything to come out of that, it would be that people learn to not brush these things under the carpet, to address these things head-on with care, with love, with compassion, and with empathy," Elwes said.