HOLLYWOOD—One night in Los Angeles, Adrian Grenier, star of the HBO series “Entourage,” encountered 14-year-old paparazzo Austin Visschedyk. Astounded and inspired by the fast-talking, faster-snapping teen, Grenier (HBO’s “Shot in the Dark”) decided to turn the cameras on Visschedyk in an effort to better understand this unique teenager’s world and gain insight into what motivates people to stalk the famous.

An intimate look at the complicated relationship between paparazzi and the celebrity culture they serve, “Teenage Paparazzo” debuts Monday, September 27 (9:00-10:45 p.m. ET/PT), exclusively on HBO.

An official selection of the 2010 Sundance Film Festival, this film takes an intriguing behind-the-scenes look at the illusion and the reality of celebrity. Well-acquainted with fans who have trouble distinguishing real life from fiction, Grenier says it is “strange that I get all this attention because I play someone who gets all this attention.” Grenier decided to hang out with Visschedyk and the “paps” to uncover what is going on in “a culture so fixated on fame that its children stalk celebrities at night.” Initially, Grenier thought he’d be on a journey to get back at the paparazzi for years, of what he believed to be breaches of privacy, but after a while the vendetta turned into a greater exploration of how they need each other.

The famous actor trails Visschedyk as he goes out to look for “the perfect shot.” When other paparazzi suggest Grenier see what it’s like on the “other side,” Visschedyk helps him purchase a camera and teaches him the basics. On his first outing as a paparazzo, Grenier joins in on the snapping as Brooke Shields is spied leaving a restaurant and gets a taste of the adrenaline.

Visschedyk’s parents have differing perceptions of their son’s “hobby.” His father sees it as a bit of a nuisance, refusing to drive his son to scope out a tip of a Cameron Diaz sighting, but his mother calls it normal teen exploration. She feels her son is “trying to figure out who he is and what his role is in the universe,” calling such behavior “typical for his age.” Despite spending late nights standing outside Hollywood clubs, Visschedyk gets good grades while being home-schooled.

Curious about the market for celebrity photos, Grenier talks to executives at OK! magazine, and film historian James Hosney explains how celebrity media attention was once controlled by the Hollywood studio system. Grenier learns from Visschedyk that stories nowadays are often invented, based on pictures taken out of context.

Grenier and paparazzi magnet, Paris Hilton, decide to conduct an experiment to see if they can create a false rumor about themselves, and begin to meet in public on a regular basis. Sure enough, the story that they are romantically involved quickly surfaces in gossip magazines, columns and blogs.

In addition to talking with Austin, Visschedyk’s family and Paris Hilton, Grenier also interviews actors Alec Baldwin; Lindsay Lohan; Eva Longoria Parker; and “Entourage” co-stars Kevin Connolly, Kevin Dillon and Jerry Ferrara. Others interviewed include TV personalities Rosie O’Donnell; Mario Lopez (host of “Extra”); celebrity blogger Perez Hilton; and comedians Lewis Black, Jaleel White and Whoopi Goldberg, among others.

Grenier also talks to psychologists, press and academics. Journalist Jake Halpern discusses “parasocial relationships,” which he describes as “weird one-way relationships where we don’t actually know the people on TV, but we feel like we do,” and admits he has a hard time not addressing Grenier as “Vince”. Mario Lopez says that at different events and around town, celebrities will come up to him as if they know each other, almost like they are part of an “unspoken fraternity.” NYU professor Thomas de Zengotita, the author of “Mediated,” observes, “In this society, if you are not famous, there is a certain very real sense in which you don’t exist.”

Adrian Grenier is the director and producer of this docu-series. In 2002, he founded Reckless Productions as a vehicle for socially responsible human stories, both documentary and fictional. He made his directorial debut with the feature-length 2007 HBO documentary “Shot in the Dark,” which chronicled Grenier’s year-long search for his estranged father.

Photographs are Courtesy: Matthew Cooke