Dewey Finn (Jack Black), a passionate but down-on-his-luck rock guitarist, gets kicked out of his band and impersonates his roommate to land a substitute teaching job at a prestigious prep school. Instead of teaching traditional subjects, Dewey transforms his class of talented fifth-graders into a rock band to compete in the Battle of the Bands. Along the way, he helps the kids discover their musical talents and confidence, while rediscovering his own purpose.