“They ARE awful. But I also think they’re fabulous. Let’s just go and say hello.”

What if young record store manager Brian Epstein had not, in 1961, after a scrappy gig in a “sweaty basement,” popped over to say hello to the band? What if, as Craig Brown wonders in “150 Glimpses of the Beatles,” Paul had done better in his exams, moved up a school year and never gotten to know George? Or Ringo had had more patience with U.S. immigration forms and succeeded in moving to Houston? Or the engine fire on a 1965 flight from Minneapolis to Portland had ended in catastrophe, cutting the band off in their prime? We are haunted by the shadows of what didn’t happen. “Think what we would have missed if we had never heard the Beatles,” the Queen once mused. As the world marks 40 years since the murder of John Lennon — gone, now, for as long as we had him — shimmering alternative histories are especially poignant. A feeling of loss is palpable.

Time-play and what-ifs are part of Brown’s formidable bag of tricks, deployed to add emotional range and a poignant twist to his comic vignettes. His biographical method — combining fragments, lists, excerpts, quotes and flights of whimsy — is executed as brilliantly here as in 2017’s glittering “Ninety-Nine Glimpses of Princess Margaret.” Interestingly, the two stories intersect. At the premiere of “A Hard Day’s Night” in 1964, in an incident that appears in both books, George approaches Her Royal Highness to point out an unfortunate hitch in the social order: “Ma’am,” he says, “we’re starved, and Walter [the film’s producer] says we can’t eat until you leave.” The princess duly departs, and thus, “for the first time, but not the last, royalty deferred to celebrity.”

Brown sets the Beatles’ rise against the declining influence of the old orders. Marlene Dietrich is spotted jealously photobombing the boys during rehearsals for the 1963 Royal Variety Performance. Noël Coward, considering their success, ponders tartly, “Perhaps we are whirling more swiftly into extinction than we know.”

The contrast between old and new worlds is amplified when Brown takes a further step back in time. At the recording of “All You Need Is Love” for television, we’re told that brass section leader David Mason once played Vaughan Williams for Vaughan Williams. In turn, the elderly composer had known, for the first 10 years of his life, his great-uncle, Charles Darwin. “From Charles Darwin to John Lennon in just three handshakes,” Brown writes: “the Beatles concertina time in the most extraordinary way.”

Within this historical sweep, Brown tells his story mosaically: The Beatles are assembled from shards of memory, no claims made of empirical authority. In fact, Brown revels in the instabilities of the past, gleefully dissecting contradictory accounts of an incident when a lock of Ringo’s hair was snipped from his head by an interloper at the British Embassy in Washington, and John’s attack on a Cavern Club emcee at Paul’s 21st birthday party. Rather than sing the biographer’s lament, Brown embraces history’s lacunae.

The narrative — presented broadly chronologically — is cut with well-known truffles of pop culture folklore: the disappointing meeting with Elvis, smoking weed with Dylan, languorous days with the Maharishi. Brown outlines a classical trajectory: meteoric rise, imperial splendor, internecine conflict, festering ruptures. Beatlemania. Sgt. Pepper. The concert on the roof.

If this sounds familiar, you probably know something of the Beatles and may not learn much from these “150 Glimpses.” But Brown is less interested in finding fresh material than finding novel ways to approach it. Often he focuses on the edges of the image, like the blurry “Mystery man” on the “Abbey Road” cover, the “toothless old geezer” in the video for “Hey Jude” or the Canadian dentist who bought one of John’s teeth at auction intending to use it in paternity suits. “The Beatles shone so brightly,” sighs Brown, “that anyone caught in their beam, no matter how briefly, became part of their myth.”

These peripheral characters contribute to the book’s distinctive flavor of wistful whimsy. All bear, or sought, the traces of the Beatles’ aura, but their identities and motives remain, like so much of the past, unrecoverable. They are hangers-on, forgotten casualties, as lost to time as the Beatles destinations that Brown tours, many now gone or repurposed. It is hard to escape the fate of their childhood homes, stuffed with refurbished kitsch but emptied of feeling.

Brown’s book is an idiosyncratic cocktail of oral history, personal memoir, tourism and biography. While he starts and finishes with the story of Epstein’s fortuitous first meeting with the band, it’s the manager’s sudden death, to which Brown repeatedly returns, that comes to feel like a central event in the Beatles story. It’s both tragedy and omen, the end of the beginning and the beginning of the end: an event to which any meaning might attach. It lends a discordant note to this riotous, hilarious book, which achieves depth through Brown’s strong feeling for both the quiet and the noisy devastations wrought by ambition, fame, personal tragedy and time.

Charles Arrowsmith is based in New York and writes about books, films and music.

150 Glimpses of the Beatles

By Craig Brown

Farrar, Straus and Giroux. 592 pp. $30