In the summer of 1969, the Woodstock music festival, eventually immortalized in a documentary film, exemplified the premise and promise of the flower-power generation. But before that year was out, another rock concert showed the other, ugly side of that coin, when the Rolling Stones watched from the stage as their own security team of Hell’s Angels assaulted, and killed, a concertgoer. The Maysles brothers were filming, and this nonfiction movie is their harrowing account – not only of a death at an outdoor music event, but of the proverbial death of the Sixties itself.