The biggest event in PBS’ fall season began with a simple idea.

Martin Scorsese asked Alex Gibney if he’d want to help produce a single film about the blues directed by Charles Burnett. Four years later, Burnett’s “Warming by the Devil’s Fire” will be joined by six other films, 20 album releases, four corporate partners, a book, radio series and Web site as “Martin Scorsese Presents the Blues” hits public broadcasting stations Sept. 28-Oct. 4.

Gibney and Scorsese’s partner, Margaret Bodde, decided one film wasn’t enough. They found six more feature-film directors with documentary experience and a passion for the blues.

“We knew we could give each director a certain territory and each would have full freedom,” says Gibney, series producer for “Martin Scorsese Presents the Blues.” “We acknowledged right off the bat that these are not the last words on the blues. This is the first word on the blues. There would be omissions.”

As directors were selected, they quickly marked their territory. Scorsese opted to explore the connection between Africa and Mississippi Delta; Wim Wenders tackled his favorite, yet obscure, bluesmen Blind Willie Johnson, J.B. Lenoir and Skip James; Clint Eastwood went for pianists; Richard Pearce told the story of Memphis; Brit Mike Figgis stuck with his heritage and went with ’60s Brit-blues invasion; and Charles Burnett made an impressionistic piece that incorporates old blues and gospel.

Marc Levin took on the city most famous for the blues: Chicago.

“These films allow directors to find their passion,” Levin says. “You do get a history lesson but it’s not straight forward.”

Each of the filmmakers was given a budget of about $1 million, financed by Paul Allen’s Vulcan Prods. and the German outfit Road Movies. Like several of his counterparts, Levin sought a contemporary angle to tell the story of Chicago and the best-known blues label of all, Chess, where Muddy Waters, Bo Diddley, Howlin Wolf, Chuck Berry and Koko Taylor recorded.

A stroke of kismet occurred after Levin began talking to Marshall Chess, son of label co-founder Leonard Chess. It turns out rapper Chuck D contacted Chess out of the blue about a blues/hip-hop project that would involve the psychedelic Waters album “Electric Mud.”

“We thought we had the beginning of a movie and we started to follow that process,” notes Levin, which would eventually lead to a recording session with Chuck D, rapper Common and the members of the “Electric Mud” band. “Marshall had waited 35 years to hear (praise) for that album. The email was divine intervention.”

Marketing of the films began in January, when PBS took a highlight reel to the Sundance Film Festival and got the directors to speak about the work at a panel. Since then, PBS and “The Blues” have had a presence at more than 100 music and film festivals, says Anne Zeiser, PBS’ director of national strategic marketing.

“The defining force was authenticity and by going to the fests, we wanted to establish our credibility,” Zeiser explains. That mission, which she says has been largely successful, was to increase awareness of the series among blues fans and film buffs.

Levin’s “Godfathers and Sons” covers some of the best-known blues musicians ever, but his verite style gives it a look not seen in any of the other pics.

“It’s actually a risky process, and we could have fallen on our face,” he says. “I want to make movies the way musicians make music. Marshall and Chuck share a love of the rawness, the realness (of the blues) — the idea that you could make great art at 3 a.m. in a club on the south side of Chicago.”