Book 4 charts the rise of Dr. Dre and Def Jam records, and introduces new branches on the "tree": Will Smith, Salt-N-Pepa, Rakim, and Biz Markie. This volume is also jam-packed with films Hollywood released in an attempt to cash in on the phenomenon, like Breakin’, Breakin’ 2 Electric Boogaloo, Beat Street, Krush Groove and more.