The film is played by JB (Jack Black Jack Black) and KG (Kyle Garth Kyle Gass), two lead singers of "tenacious D", and tells how they "built" the greatest band in the world step by step. JB was born into a very conservative family, and his father has always been firmly opposed to JB playing rock music, the "voice of the devil". But that didn't stop JB from becoming a true believer in rock music. So little JB fled the suffocating home and headed for Hollywood guided by Ronnie James Dior, the god of rock and roll. One day, JB was attracted by a moving melody in the street, and it was KG who played Bach's Concerto in E minor. Then the two set up the world-shaking band "tenacious D" and moved on towards their dream. This film is not an autobiographical film in the strict sense, and many passages are designed to create a comedy effect. But that doesn't stop you from being amused by the parodies of these two fat men and feeling their love of rock music in the soundtrack of "tenacious D."