How strange, then, to find that suddenly the buzziest forthcoming title of the season was an enigma, one without an announced title or author, its cover a blank space waiting to be filled. On Amazon, the book in question appeared as “4C Untitled Flatiron Nonfiction Summer 2023 Hardcover,” with a byline that read “Flatiron Author to be Revealed July 2023.” Even the release date — July 9 — is puzzling. That, the curious have noted, is a Sunday, and books are almost always released on Tuesdays. (Amazon founder Jeff Bezos owns The Washington Post.)

Despite this factual void — or perhaps because of it — the book proved to be a hit. On Tuesday, Variety reported that the $45 volume had risen as high as No. 2 on Amazon’s mercurial books bestseller chart and was similarly dominant on Barnes & Noble’s site.

Those purchases seem to have been driven by a group of close, sometimes even obsessive, readers: Swift’s fans, who have convinced themselves that the singer-songwriter is the book’s yet-to-be-revealed author.

These theories were wrong, Variety correctly argued, and Flatiron confirmed Thursday that the book was actually an oral history of the Korean boy band BTS, according to the New York Times. But that didn’t stop the faithful at first.

Fan speculation about the book’s origins ballooned over the weekend, reportedly starting with a TikTok video from the Good Neighbor Bookstore in Lakewood, N.Y., about a mysterious book that might have Swift ties. Then a screenshot of a message to booksellers surfaced, noting the unusual Sunday release date, promising that more information would be available June 13 and disclosing that the book was expected to have a first print run of 1 million copies. This sent Swiftie social media into overdrive — something that huge had to be by a celebrity, they figured, and July 9 is a significant day for Swift fans because of a lyric in her 2010 ballad “Last Kiss.” And 13 is of special importance in the Swiftverse, not least because the singer calls it her lucky number.

That game of social media telephone soon spread, and the speculation found its way onto other platforms. (As one representative tweet put it: “What’s the most unhinged thing you’ve done because of Taylor Swift? I pre-ordered a book I know nothing about on the SLIGHT chance it’s her memoir.”) Maria Betts, 21, saw her Tumblr post take off when she called attention to an Instagram post from Blacksburg Books in Blacksburg, Va., about the mysteriousness of the title. While the bookstore’s post was vague — allowing only that “we have our guesses” — Betts added the caption: “All i’m saying is this does feel like a Swift thing to do.”

Betts said she first spotted the store’s Instagram on a Swift fan Discord server and was intrigued. “I think the most compelling piece of evidence was the release date, because who releases a book on a Sunday?” she told The Washington Post in an email. “I’m really intrigued to see what this mystery book ends up being, and even if our theories are wrong, you just have to laugh and put the memory in the folder of ‘times I really loved being a Swiftie.’”

After all, being a part of the extensive and deeply loyal Swift fandom means constantly hunting for clues, because the pop megastar has spent her entire career leaving “Easter eggs” in her work — whether she’s hiding coded messages in her lyrics about the subject of a song or using numerology to drop hints about an upcoming project. Swifties have been trained and encouraged by the singer to analyze and theorize about everything. As fans have said, they know that Swift delights in these games and pays attention to the smallest details, so it makes them feel like they have even more of a personal connection with their idol. (This isn’t even the first time they’ve turned a book into an improbable bestseller.)

How the search for clues in Taylor Swift’s music became all-consuming

The timing was impeccable, because fans were primed for another big theory. On Friday, Swift confirmed months of online speculation when she surprised a sold-out stadium crowd in Nashville by announcing that “Speak Now (Taylor’s Version)” — the next album in her quest to rerecord her first six albums after a dispute with her former record label — would be released on July 7.

In her social media announcement about the “Speak Now” rerelease, Swift used the phrase “Dear Reader,” which is, yes, the title of a track from her latest album, “Midnights” … but also could suggest a book. One fan even dug up Swift’s liner notes from the original “Speak Now,” in which she refers to a book.

Variety noted that some of the speculation derives from the fact that the digits in the announced page count of “4C Untitled” — 544 — add up to 13.

Soon after the investigative fervor began to build, Blacksburg Books deleted its Instagram post, and Good Neighbor Books deleted its TikTok video, both in response to requests from Flatiron. While Blacksburg Books’ first post hadn’t made any clear claims about the book’s nature, its Monday follow-up was almost conciliatory, noting, “We were asked by the publisher to take down that post, which we did.”

In a phone interview on Wednesday afternoon, Ellen Woodall, manager of Blacksburg Books, explained that she initially saw speculation about the title on Facebook groups for independent booksellers.

“I didn’t pay much attention, but then a customer actually found it on the Macmillan website,” Woodall said. (Macmillan Books owns Flatiron.) The customer was “speculating about the date and the page numbers, so I thought it might be fun to throw it out there and see what our followers thought it was.”

Woodall, who acknowledged that Blacksburg Books has “a lot of Swifties on staff,” again stressed that she has no idea who the book’s actual author is. “We’ve had a fantastic time watching all the speculation occur, but we’re not engaging in it,” she said. The store has also canceled preorders of the book that came in.

Bob Lingle of Good Neighbor Bookstore, who posted the now-deleted TikTok, also said over the phone that he’d learned about the possible connection through bookseller Facebook groups. After he posted his video, he was inundated with preorders, accumulating more than 100, all of which he, like Blacksburg Books, subsequently canceled when he learned that the book probably wasn’t what he’d thought it was. The experience was ultimately a disappointing one for him, since surprise releases often play to the advantage of larger retailers.

“Publishers on their time will put out what the book is, and generally, with Amazon having control of the market, people will just rush to Amazon to place their order,” he said. This time, he said, he thought, “Well, if I can get ahead of this one, maybe it will be worth it. And it wasn’t.”

“I hope that other publishers see this and realize, If we do this it could become a nightmare,” Lingle said. “Just tell us what the book is.”

Flatiron did not respond to multiple requests for comment by email and phone. Swift’s representative also did not respond to a request for comment.

As of Wednesday afternoon, the mystery title had slipped to No. 34 on Amazon’s bestseller charts — still an impressive feat for a book with a heavily pixelated “No image available” logo in place of a cover. Up at No. 5, meanwhile, was a slim volume that, coincidentally, Blacksburg Books had spotlighted on its Instagram account earlier in the month: “Taylor Swift: A Little Golden Book Biography.” On its cover: a cheery drawing of the singer-songwriter forming her hands into a heart.

For now, at least, that’s all Swift’s most ardent admirers will get. Still, they can fantasize that they may yet see “4C Untitled Flatiron Nonfiction Summer 2023 Hardcover (Taylor’s Version).”

This article has been updated.