Sean Penn has spent the majority of his career in front of the camera. In 1982 when he made a splash in Amy Heckerling’s Fast Times at Ridgemont High, he was the young, blonde, carefree surfer dude. By 2007, at the age of 47, Penn has turned himself into a thought- and discussion-provoking actor-writer-director-producer. Throughout his journey he has starred in Carlito’s Way (1993), Dead Man Walking (1995), U Turn (1997) and 21 Grams (2003) and made a name for himself as the dark and brooding actor’s actor. Now he’s stepping behind the camera for the fourth time, detailing another man’s life-changing journey in the drama Into the Wild, released in the U.S. on Friday, September 21.

Based on the book of the same name by Jon Krakauer, Into the Wild stars Emile Hirsch as the young Christopher McCandless who rids himself of all monetary and personal possessions to live on his own in the Alaskan wilderness. The idea for an adaptation first came to Penn after reading the book more than 10 years ago. “I read it from cover to cover twice before I went to sleep,” he says. “Then I got up the following day, whatever time it was, and started right away trying to see if I could get the rights. I thought the story was instantly indelible and deeply cinematic in its characters and its landscape in every way. It hit the same nerve with me that I think it hit with most people who read it.” And most people who will see the movie — or at least that’s what this moviemaker is banking on.

“Sean is an incredibly special person, and let’s say you’re standing on the edge of a pool wondering if you should jump in, Sean’s the perfect person to push you,” says musician Eddie Vedder, who contributed original music to the film. Of course, most people know of Penn’s sometimes extreme nature (see his much-hyped August meeting with Venezuelan leader Hugo Chavez) and his determination to get things done. But it’s the little details that add to all of Penn’s moviemaking efforts. And this time around, it’s no different, with the writer-director chronicling the life of McCandless in his two-year solo journey that ended in death. Says Krakauer: “Sean has made the kind of movie I suspect will leave an impression on people for a very long time. It doesn’t spoon-feed you, it’s an intense movie, but it makes you wonder.”