The Holy Grail of concert films—with an eye-popping lineup including Chuck Berry, The Supremes, Marvin Gaye, Smokey Robinson, The Beach Boys, and The Rolling Stones—went unseen outside the bootleg circuit for decades due to rights disputes. Seen in its full glory, it’s a showcase for American pop music at the undisputed height of its passion, humor, pathos, virtuosity, and vigor. Lesley Gore’s voice was never more commanding, and Mick Jagger shakes a mean maraca, but the undisputed highpoint is Brown’s four-song set: a sustained, expertly modulated outpouring of passion performed—fittingly, for an artist who began his career as a gospel singer—with the sweaty, bone-straining urgency of a man who feels his soul is on the line.