History is written by the victors—and as a corollary, winners usually become the focus of music documentaries. When it comes to the tragic tale of the Band, guitarist and main songwriter Robbie Robertson definitely has emerged triumphant. Three of the five members of this influential rock group are dead, and the other survivor, keyboardist Garth Hudson, shuns the spotlight. Hudson doesn't even speak in Once Were Brothers: Robbie Robertson and the Band—although he was interviewed.

The great irony of the Band is that they became pioneers and paragons of what came to be known as Americana, although only one member (awesome drummer/vocalist Levon Helm) was American. The rest of the Band—Robertson, Hudson, bassist Rick Danko, and pianist/vocalist Richard Manuel—were Canadians who cut their teeth in rockabilly wild man Ronnie Hawkins's group as the Hawks, and then further honed their chops while on tour with Bob Dylan in the mid 1960s, as that folk icon shifted into his electric-rock phase. Those apprenticeships, though, helped to forge their creativity, and the rest is musical history.

Once on their own, the Band congregated in Saugerties, New York, and created music that broke with their past endeavors in the basement of a house known as Big Pink. Robertson strove for originality, and at their best, the Band created a mournful sound that lifted you heavenward. They harnessed an earthier-than-thou, gospelized rock that seems nonchalant—and ageless. What really distinguished the Band was their four vocalists, who emitted some of the most soulful sonorities ever to come from Caucasian males. Respect to director Daniel Roher for including footage of two of the best and most soulful Band songs: "Up on Cripple Creek" and "Chest Fever."

With Once Were Brothers, Roher presents a conventional contextualizing rock doc with marquee-name talking heads—Van Morrison, George Harrison, Bruce Springsteen, et al.—and efficiently reveals Robertson's early family life (his mother was indigenous, his father Jewish) and musical evolution. Robertson is an articulate, passionate memoirist; the film is based on his 2016 autobiography, Testimony. With equanimity, he registers the Band's soaring highs and devastating lows, while his French ex-wife Dominique adds crucial observations about the inter-band dynamics and substance abuse that dogged the members. Tracing a story of relentless, upward mobility through the music industry, the doc emphasizes Robertson's inner strength and boundless ambition, which helped him to avoid the booze- and drug-related pitfalls that afflicted his mates.

For fans of the Band, this film will inspire tears of sorrow and joy, if not rage. Now more than ever, their music stirs emotions with a profundity that feels religious, but without the stench of sanctimony.