It’s surprising that his early role models were so mainstream: Red Skelton, Sid Caesar, Jerry Lewis. He aspired to such a clean, white-guy style that his early image was that of an also-ran Bill Cosby — at a time when there was room for only one Bill Cosby in show business. (At that stage in his career, Pryor actually thought he was clean enough to emulate what Mr. Cosby called his “Joe Q. Public” persona.) After a stint in the Army (from which he was soon discharged as mentally unsuitable) and on the Chitlin Circuit (where the risqué routines of Redd Foxx would come to sound like a Boy Scout’s oath compared to what Pryor learned to dish out), he arrived in New York “with $10 in his pocket and patent leather shoes on his feet, hoping to glide through the door that Cosby had opened,” Mr. Saul writes. “But first he had to find it. He had only the faintest idea where to start looking.”

Mr. Saul takes a lot of such material from Pryor’s 1995 memoir, “Pryor Convictions and Other Life Sentences.” But his array of new sources include people like the filmmaker Henry Jaglom, who, as an aspiring young actor-comedian from a wealthy family, made Pryor a friend and houseguest. Mr. Jaglom watched Pryor’s early experiments with improvisation and learned a lot about the difference between a white liberal’s racial politics and those of a black kid who didn’t come from a family of pacifists. Mr. Saul has also found a lot of people who had violent conflicts with the famously mercurial Pryor but did get to see him at very close range.

Especially women. Their stories about him are anything but funny, and not even knowledge of what Pryor must have learned during his boyhood can erase the horror that he inflicted as an adult. The stories of beatings are just business as usual; the woman beaten about the head with two brandy bottles, one in each fist, takes it up a notch. Those who chose to stay with him had to get used to coming home and finding him in bed with somebody else (usually female, but not always; he acknowledged his bisexuality). Sometimes, they were ordered to participate, willingly or not. One escaped for a while but was eventually wooed back with gifts including a chinchilla coat. She came home a while later to the ghastly smell of chinchilla on fire.

Extrapolate that kind of behavior to the workplace, and you get some idea of what Pryor was capable of doing on a movie or television set. He became a sufficiently huge star to have networks and studios chasing him, and for a while, he found the money irresistible. But he especially hated television, because it meant so many fights with network executives about his material. (Mr. Saul dissects the few shows he did very carefully.) And even his best film work, as in Paul Schrader’s “Blue Collar,” wound up being done in an atmosphere of extreme antipathy. His self-loathing about television led him to predict accurately that he would only be able to do the work if loaded to the gills with booze and cocaine. Result: He would see sketches and not remember having performed them.

Mr. Saul makes a great point of how smart and principled Pryor could be about racial nuances, which is part of why his reputation for greatness has only grown. Pryor wrote a lot of “Blazing Saddles” and expected to play the black cowboy (another of his childhood heroes was the campy cowboy Lash LaRue), but he was deemed unbankable. So he didn’t make his first film with one of its stars, Gene Wilder, until they were paired in “Silver Streak.” That film has a bathroom scene in which Mr. Wilder’s character puts on blackface to disguise himself. Pryor’s character, as originally written, is supposed to be toothlessly amused.