Is American Ganster film starring Denzel Washington based on a true story or book?

Yes, American Gangster is based on a true story. It's inspired by the life of Frank Lucas, a drug kingpin who operated in Harlem during the 1960s and 1970s.

The film draws heavily from the 1999 New York Magazine article "The Return of Superfly: Frank Lucas's Wild Ride From the Streets to the Witness Stand," written by Mark Jacobson. This article, which forms the foundation of the film's narrative, tells the story of Lucas's rise to power, his involvement in the heroin trade, and his eventual downfall.

However, it's important to note that, like many films based on real events, "American Gangster" takes some creative liberties with the story. While it stays true to the core elements of Lucas's life, certain details and events are dramatized or fictionalized for cinematic effect.