Norm Macdonald peaked in the '90s, with Saturday Night Live, Dirty Work, and several legendary live TV appearances, from the ESPYs to Conan. The Canadian comic was O.J.'s greatest detractor, Burt Reynolds' most memorable imitator, and David Letterman's biggest fan.

In an SNL cohort dominated by friendly hams like Adam Sandler and Chris Farley, Macdonald stood out for how thoroughly he refused any complicity with the audience; his "Weekend Update" was an oddly confrontational mix of dry sarcasm and non-joke jokes. Viewers liked it so much that Macdonald's "Update" has been credited with setting the stage for Jon Stewart's The Daily Show. When Macdonald got fired (ostensibly for his jokes about O.J. Simpson), it made a big splash. Macdonald immediately went on Letterman to talk about it — Letterman lovingly called him a quisling — and returned to SNL a year later to host with a funny but pointed monologue. "I don't know if you remember this, but I used to be on this show," Macdonald said. "That's where I did the make-believe news jokes. That was me!" Macdonald's fortunes declined after that; he got a sitcom on ABC called The Norm Show (here's the Pokémon-themed episode), but it was canceled after being moved to the Friday night slot.

And then he seemed to all but disappear.

Since then, Macdonald has been inching back into the spotlight he half-resents, with his popular video podcast, Norm Macdonald Live (which returns this month for a third season), a half-serious campaign to host The Late Late Show, and a Twitter account which — when it isn't spilling the beans on SNL history in fascinating bursts that are subsequently deleted — maintains a pure, slightly bizarre focus on golf. The Washington Post ran a great profile of him a couple of weeks ago, and his first book, a "memoir" called Based on a True Story, drops Sept. 20.

May it break you the way it has broken me.

There are two things you should know about the book: First, it is easily the most ambitious thing Macdonald has ever done. Second: It is pretending hard to be nothing of the kind.

That tension is visible even on the cover, which shows Macdonald's name in bright lights — or would, if only the neon sign had all its letters, and hadn't rusted, and it were night. But it's daylight on the cover of the book: Macdonald's disembodied head appears grinning in the middle of a switched-off sunburst, and you are reminded, looking at it, that you never felt good watching his "Weekend Update" on Saturday Night Live. Macdonald's affable dimples were always at odds with the light contempt in his eyes. It seemed he hated himself and you just a little more with every joke: him for telling it, you for laughing.

The book begins coherently enough, albeit in the voice of a dispirited, washed-up, oddly sincere Norm: "Stand-up comedy is a shabby business," he says, "made up of shabby fellows like me who cross the country, stay at shabby hotels, and tell jokes they no longer find funny." This dissolute, drunken Norm wakes up with a woman he doesn't remember meeting in his bed and discovers he's been reported dead on Wikipedia; the incident inspires him to write about his life. "And as I look at her and wonder who we were last night, I come up with a title for my book," he says. "I'll call it Based on a True Story, because it comes to me that there's no way of telling a true story. I mean a really true one, because of memory. It's just no good."

That poetic meditation on memory and truth conceals some downright diabolical authorial intentions.

Based on a True Story turns out to be Macdonald's experiment in hyperliterary comedy. It's disorienting, funny, sometimes stupid, and often wildly beautiful. That's the weird part. After a couple of amusingly implausible anecdotes about gambling, drugs, and Hollywood, a chapter on his childhood erupts into waves of unbelievable lyricism — with reflections on aesthetics and memory and trauma so poetic I kept sending passages to a pal who's a Nabokov scholar to see if they reminded her of him too (even as I pictured Macdonald rolling his eyes at the comparison). Indeed, Macdonald likes to say he's got no book-learning but likes to read "literature": He loves Gogol and Tolstoy and once told Russell Brand that while he quite liked My Booky Wook, it was no Speak, Memory.

Macdonald has always had two sides. There's the drunk-seeming sports fan who slurs and swears and claims not to know what words mean. He likes to chat about prostitutes and how little he's studied. The other is the father of all "Dad jokes," a twinkly Depression-era "fellow" who uses phrases like "put me in mind of" and "a pickler's fortnight" and created a viral sensation in 2008 when he mystified the bloodthirsty audience at Bob Saget's Comedy Central roast by sticking exclusively to material from his father's joke book: "He has the grace of a swan, the wisdom of an owl, and the eye of an eagle," Macdonald said of Greg Giraldo. "Ladies and gentlemen, this man is for the birds!"

Those facets play well off each other. Sometimes they alternate, as in this episode of Norm Macdonald Live, where at 3:18 Macdonald exclaims, "That's yeoman's work!" and then says, "Follow-up question: What's a yeoman?" But they certainly don't form a cohesive whole, and neither do the various strands of Based on a True Story.

The real Norm is neither the fellow nor the boor — his text message exchanges with The Washington Post's Geoff Edgers are as intimate a portrait as we're likely to get of the man himself. Here are some things we do know: The real Norm Macdonald wept as he said goodbye to David Letterman. The real Norm Macdonald has a gentlemanly strain that cuts both ways; he didn't want to do "Weekend Update" with "a lady" because she would "ruin" it. He fired his agent after he suggested he open for Adam Carolla. He didn't show up at a surprise Comedy Store gig with Louis CK and Chris Rock because even though he would "destroy," it would lead to nothing: No one would mention him. The real Macdonald worries a great deal about dying. He struggles with faith, prevaricates about his age, and says he never drinks. He was cripplingly shy as a child. He loves "super-old people" for the perspective they offer, suffers from Stendhal syndrome, and has lost everything to gambling three times.

The real Norm claims to love straightforward comedy.

We get some stunning tidbits from the real Norm in Based on a True Story, but he vanishes into a haze of performative self-deprecation and dry wit anytime we start getting too close. Without going into details, I'll just note that the "memoir" begins to fall apart when a resentful ghostwriter starts chiming in. Only Norm Macdonald would ghostwrite his own ghostwriter. Only Norm Macdonald would loudly proclaim a preference for layer-less comedy while borrowing heavily from Nabokov's Pale Fire.

This last bit is worth dwelling on: Macdonald has long maintained that his ideal joke is so self-evident that the punchline is the same as the setup (a goal he achieved with a "Weekend Update" joke about Julia Roberts and Lyle Lovett). He says he dislikes cleverness and innuendo: "Isn't there something cowardly about, like, cloaking it or something?" he said to Marc Maron in an interview. "I don't know psychological shit but it must be some level of dissociating yourself from what you actually mean." He enjoys performing self-deprecation — as when he dismissed those who interpreted his Comedy Central roast as a master class in comedy trolling: "When people say I got it, I was like: What the f--k is there to get?"

A lot, it turns out. Macdonald's "memoir," for instance, starts off with big confessional promises: "It'll be the truth, every word of it, to the best of my memory," he writes. "And I won't just scratch the surface either, no sirree, Bob. I'll claw and tear into this showbiz career of mine and I'll let the filth fly, like a mad dog digging up bones he buried deep and long ago." The promised candor never materializes; it just makes fun of you for expecting it: ("The ugly little secret in Hollywood," he writes in Chapter 13, "was that Rodney Dangerfield never got any respect.")

Instead, the book becomes a complicated nest of references. It weaves in one of the more notorious scenes from Macdonald's 1998 movie Dirty Work. It includes a downright Tolstoyan version of the moth joke. It addresses rumors about his firing from Saturday Night Live as if the circumstances were reversed. There has never been a less straightforward book. It's playful and spry and just unbelievably cagey.

But it broke me, and I'll tell you why: Macdonald is a pretty extraordinary wordsmith, capable of working in an impressive range of styles and genres. But despite the rollicking fun he had with this book (and I recommend reading it because it's a wild ride) those registers don't cohere. Parts of Based on a True Story affected me much more deeply than I expected; frankly, I got a touch of Stendhal Syndrome myself, and the wild swings in register between lyric and farce don't square with the difficult beauty of some of the material. I hope Macdonald tries a less manic approach next time; he has a masterpiece in him.