Cry Baby: The Pedal That Rocks The World tells the story of the wah wah effect pedal, from its invention in 1966 to the present day. Musicians, engineers, and historians discuss the impact of the pedal on popular music and demonstrate the various ways it has been used, as well as how its evolution has improved the ability of artists to express themselves musically. The film features interviews with Brad Plunkett, the inventor of the pedal, plus many other musical luminaries such as Ben Fong-Torres, Eddie Van Halen, Slash, Buddy Guy, Art Thompson, Eddie Kramer, Kirk Hammett, Dweezil Zappa, Jerry Cantrell and Jim Dunlop. These professionals explain how a musical novelty transcended convention and has become timelessly woven into the fabric of modern pop-culture.