A documentary crew tails the Rolling Stones for a leg of their 1969 North American tour and unwittingly captures one of the nastiest, bloodiest all-day concerts in music history - the infamous Altamont Speedway show. Mostly pieced together from ambient handheld shots taken on the day of the festival and shown sans narration, it's a stunning stream-of-consciousness presentation of the crowds, cultures and events leading up to the angry, violent personality of the gig itself.

It's stunning just how little foresight and planning went into this event, as two days beforehand organizers were still trying to settle on a venue with little or no mind paid to such vital elements as parking, waste management or security. Maybe that kind of mindset would have worked for a small or mid-sized show, but with a crowd in excess of 300,000 showing up to take in what was being portrayed as “The Woodstock of the West," the only possible outcome of such an awful strategy is total, unmitigated chaos. And that's what they get, as a pushy, balls-tripping audience runs headlong into a moody, fight-spoiling security outfit and lights a tragic set of fireworks. A painfully slow degradation of civility and humanity set to music, it's a dark counterpoint to the radiant, optimistic attitudes seen at Woodstock.