In “Based on a True Story,” Mr. Macdonald lists the “Top 25 Weekend Update Jokes of All Time (in no particular order),” starting with one from Chevy Chase’s tenure as host and then 24 from his own. There’s only one joke included about the O. J. Simpson trial.  Mr. Macdonald feasted on the Simpson case during his time as anchor. (A compilation of the brief setups and punch lines on YouTube runs to more than 26 minutes.) When Mr. Macdonald was dismissed from that segment, the move was widely thought to have been orchestrated by the NBC executive Don Ohlmeyer, a friend of Mr. Simpson’s. (Mr. Ohlmeyer denied that his friendship with Mr. Simpson was behind the decision.)  So it’s belated inside baseball for Mr. Macdonald to take on Mr. Ohlmeyer in this memoir. But it’s scathing and funny, too. In the comedian’s wicked reimagining, Mr. Ohlmeyer was upset when the O. J. jokes stopped, leaving him without material for teasing his buddy. “I’d give him the business about this whole double-murder thing,” Mr. Macdonald has his fictional version of Mr. Ohlmeyer say. “Lay a couple of zingers on him from your Update segment. Boy, old O. J. would see red, I’m here to tell you. And the more steamed he got, the funnier it struck me.”  A memoir in the sense that it’s roughly organized by the timeline of Mr. Macdonald’s life and career, this book is absurd fiction in many of its details, even the most basic ones. “I was a hick, born to the barren, rocky soil of the Ottawa Valley, where the richest man in town was the barber,” Mr. Macdonald writes. He actually was born and raised in Quebec City. Likewise, he may have had an intense crush on Sarah Silverman during their time on “Saturday Night Live” together, but he most probably didn’t have Colin Quinn help him arrange a hit on the life of Dave Attell, a fellow comedian and rival suitor.  The book is also structured around a fictional (or partly real, who’s to say) road trip to Las Vegas undertaken by Mr. Macdonald and a friend. Mr. Macdonald has spoken about his real-life gambling problems, though the book mostly presents them as just more outlandish material. (His best bit on the subject: “I remember a psychiatrist once telling me that I gamble in order to escape the reality of life, and I told him that’s why everyone does everything.”)  Mr. Macdonald’s off-kilter work has a philosophy behind it, which is expressed in the book this way: “A joke should catch people by surprise; it should never pander. Applause is voluntary, but laughter is involuntary.” Some of what’s here won’t be a surprise to fans. The book recycles pieces of Mr. Macdonald’s stand-up, like his claim that he was in “great shape” as an infant. At 1 year old, he writes: “I even looked good for my age. Strangers would always approach me, smiling, and they’d say, ‘Look at you, little boy, what are you, zero?’” We’re also treated to the “moth joke,” a three-page Dostoyevskian setup for a one-line gag. (It reads more smoothly than the version once shakily delivered on air to Conan O’Brien.)  The book doesn’t stray far from stand-up and “Saturday Night Live,” and why would it? Mr. Macdonald’s one big starring film vehicle, “Dirty Work” (1998), was called “leaden, taste-deprived attempted comedy” in The New York Times. Other roles have included an uncredited bartender in “Deuce Bigalow: Male Gigolo.”  Fans will know going in but others should be forewarned that Mr. Macdonald’s punch lines, cartoonish as they are, are often built on grim foundations: prison rape; drug deals gone very bad; a young boy whose dying wish is to kill a baby seal.  It’s easy to believe that Mr. Macdonald is unusually funny while also understanding the limits of his career outside of clubs. He’s an oddball by nature who also seems to have genuinely cultivated a disregard for conventional success. This memoir’s evasive clowning is in keeping with all that. Some might hate it, but most won’t completely hate it.  Based on a True StoryBy Norm Macdonald, with a foreword by Louis C. K.240 pages. Spiegel & Grau. $28.  A version of this review appears in print on December 22, 2016, on Page C4 of the New York edition with the headline: A Comedian’s Embroidered Life. Today's Paper|Subscribe
This stand-up’s so-called memoir is most direct, and most convincingly self-loathing, about the job of comedy. Many of its details are fiction.