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, SEPT. 27 (9:00-10:45 p.m. ET/PT), exclusively on HBO.

An official selection of the 2010 Sundance Film Festival, TEENAGE PAPARAZZO 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.” He decides 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.

Grenier 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.

Curious about the market for celebrity photos, Grenier talks to executives at OK! magazine. Film historian James Hosney explains about 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.

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