This episode is just dedicated to guitar heroes such as Santana, Eric Clapton, Eddie Van Halen etc. The driving force of electric guitar is what defined rock n roll music. As Jeff Baxter commented, no electric guitar, no rock n roll.
Artists each express love for their instrument in this episode, and how the instrument transformed their lives. To most of them this was their way out and to express themselves. As Bruce Springsteen puts it "The smell of electric guitar, it's like smell of grass, it brings certain feelings within you". Eddie Van Halen puts it as "When you walk into a music store, it's like walking into a candy shop".
If you love rock guitars, this episode is a must see.