There aren't many famous rock bands that have lasted 50 years with the same three members.

None, probably--except for ZZ Top.

If you're a big fan of the Texas boogie-blues trio--guitarist-vocalist Billy Gibbons, bassist-vocalist Dusty Hill, and drummer Frank Beard--you might want to check out a new documentary on them that plays at the Rio Theatre this Tuesday (September 3).

It's called ZZ Top: That Little Ol' Band from Texas, and was directed by Toronto's Sam Dunn, who's done impressive work in the past codirecting documentaries on other rock legends, like 2010's Rush: Beyond the Lighted Stage and 2014's Super Duper Alice Cooper. 

Here's some promotional bumph:

"Produced by the Emmy Award-winning Banger Films, ZZ Top: That Little Ol' Band from Texas tells the story of how Billy Gibbons, Dusty Hill, and Frank Beard became one of the biggest, most beloved bands on the planet, all while maintaining a surrealist mystique that continues to intrigue fans and entice onlookers 50 years after the band's inception.

"Buoyed by candid band interviews, never-before-seen archive, animation, celebrity fan testimonials (Billy Bob Thornton, Joshua Homme and more), and an intimate performance at the legendary Gruene Hall shot exclusively for this documentary, That Little Ol' Band runs the gamut, from the absurd to the poignant, from squalid Texas bars to MTV heroics, all in celebration of this notoriously private, but larger than life, power trio.

"In the end, ZZ Top: That Little Ol' Band from Texas unravels the extraordinary tale of a band whose image we know, but whose story we don't."