At the time of the epochal concert in Boston on April 5th 1968 that provides the central focus for this book, James Brown was arguably the most powerful, charismatic black figure in American life. Yet just as crucial as the concert itself, staged hours after Martin Luther King's assassination, was what flowed from it.

In the months and years that followed, James was emboldened and empowered, unleashing innovative recordings including Say It Loud I'm Black and I'm Proud, Licking Stick and Give It Up or Turnit a Loose. Perfectly, percussively suited to the later art of sampling, these and other Brown releases would fuel rap's coming-of-age generation, underpinning records by Run DMC, Schooly D, Public Enemy, Eric B and Rakim, Big Daddy Kane and so many others. But more than just the beats, those later musicians were sampling Brown's aura. James had already turned his youthful incarceration and later battles with record companies to his advantage: with the nation teetering on the brink of racial implosion following MLK's death, his inspirational senses of self, drama and destiny came to the fore.

As Chuck D says in his foreword to Sullivan's suitably electrifying book, "James stood out from the pack - outta sight and outta sound." Prefiguring James's arrival at the Boston Garden, the writer expertly captures the mood of upheaval, tension and anger that gripped both his native city and America at large following King's murder. The detailed and compelling description of JB's Boston performance comprises one of the most engrossing descriptions of the man's stage presence ever written, and the show emerges as nothing short of a healing ceremony for a scarred, shellshocked community and its slain figurehead.

Cutting back and forth from the show, Sullivan unearths fascinating detail. Intensive negotiations were needed to persuade Boston Mayor Kevin White to rethink his potentially calamitous inclination to ban the concert, and also to allay Brown's fears about the contractual ramifications that televising the show - twice - might have. In the event, Boston was largely free of the riots that rocked other American cities; and in the days that followed, James's status was acknowledged as he flew to flashpoints in other parts of the country.

Sullivan's scope is broad. Wide-ranging historic influences in music, comedy and chitlin circuit revues are brilliantly telescoped, giving a fuller understanding of both Brown's art and his persona, as are the contradictory elements that would later lead The Godfather of Soul to cross the political divide, causing a man once considered an unfettered threat to the status quo to veer towards becoming an arch conservative. Preaching racial pride and patriotism, endorsing both Hubert Humphrey and Nixon James, would in time cause a backlash among the constituency he once spoke to with such authority. Indeed, the book's earlier momentum fades as Brown's final years are assessed, and his superhuman mask starts to slip.

But Sullivan's achievement is to put Brown's life and worldview in an ever-compelling context. Stubborn, hardheaded self-absorption meant James was duty bound to follow his own, sometimes contrary, path. But when the heat was really on, those same qualities made him the living embodiment of a cultural dynamo and shamanic healer.