NEW YORK » Shortly after sunrise Tuesday, the doors opened at the Old Courthouse Museum in Monroeville, Alabama, and a bell tolled.

In the hometown and residence of Harper Lee, it was time to start a marathon and occasionally painful reading of "Go Set a Watchman," the second book no one ever thought they would see from the author of "To Kill a Mockingbird."

Lee fans worldwide stayed up late, awakened early and dashed off during meal breaks to pick up a copy of the year’s most anticipated novel, "Go Set a Watchman," which came out Tuesday after months of the most unusual pre-publication attention in memory. From the moment publisher HarperCollins announced "Watchman" in early February, reactions of ecstatic disbelief have been shadowed by concerns about the book’s quality, the 89-year-old Lee’s involvement in the release and the jarring transformation of Atticus Finch.

"I don’t think it’s going to damage Harper Lee’s legacy," Susan Scullin, a reading teacher in New York City, said of "Watchman" as she prepared to buy a copy at the Barnes & Noble in Manhattan’s Union Square.

"It might damage Atticus Finch’s legacy, and that makes me a little nervous."

Booksellers from Cambridge, Massachusetts, to Downers Grove, Illinois, opened at midnight Tuesday, while Barnes & Noble stores began selling copies at 7 a.m., two hours earlier than usual. Pre-orders have already made "Go Set a Watchman" one of the year’s top books and did not let up despite lukewarm reviews and the unwelcome news that Finch, one of the all-time literary heroes, was a bigot in "Watchman."

Amazon.com has called "Watchman" its most popular pre-order since the last Harry Potter book, which came out in 2007. At Barnes & Noble, the comparisons were not to a phenomenon like Potter, but to a follow up: Mary Amicucci, the superstore chain’s vice president for adult trade and children’s books, said that pre-orders were the highest since the 2009 release of Dan Brown’s "The Lost Symbol," his first novel after "The Da Vinci Code" and itself a million seller.

Sales for "Mockingbird," already a consistent favorite, have doubled at Barnes & Noble since "Watchman" was announced. The book’s first printing exceeds 2 million copies.

In slightly varying accounts, Lee attorney Tonja Carter has said she came upon the "Watchman" manuscript last year while looking through some of the author’s papers. "Watchman" was written before "Mockingbird," which won the Pulitzer Prize in 1961. But it takes place 20 years later, in the 1950s. Carter and literary agent Andrew Nurnberg have also speculated that Lee planned a trilogy of novels, although HarperCollins in its "Watchman" press notes cited "scant reference to support this theory."

"Watchman" finds a grown-up Scout, now living in New York, visiting her native Maycomb, Alabama, and observing a community terrified by the Supreme Court’s recent ruling that school segregation was unconstitutional. Scout herself is shaken when among those joining the racist mob is the man who in "Mockingbird" stood against it, her father, Atticus.

In Monroeville, which has long had an ambivalent relationship with Lee, only around 20 people were in attendance as volunteers took turns reading from "Watchman." Ann-Michael Winstead, 20, endured reciting Atticus’ ugly warning to Scout: "Do you want your children going to a school that’s been dragged down to accommodate Negro children?"

Winstead wiped her eyes after the reading.

"It was tough. You grow up with this book (‘Mockingbird’) … You think of him as the perfect gentleman, colorblind," she said as she choked back tears.

At a reading Tuesday night in Manhattan, the actress who played Scout in the 1962 film adaptation of "Mockingbird" praised the new book. Mary Badham, now 62, said she admired how Scout is "still pushing buttons every chance she gets" and added that such recent tragedies as the church shooting in Charleston, South Carolina, meant that the racial themes in "Watchman" remained relevant.

"It all comes down to education," said Badham, who explained that when she speaks to students she makes them say, then scream "the root of all evil is ignorance."

Shoppers at the Waterstones bookstore in London’s Piccadilly Circus were hopeful as they used their lunch hour Tuesday to pick up copies of "Go Set a Watchman." Some said they planned it to be their holiday reading, others said they wanted to know more about the beloved characters in "To Kill a Mockingbird."

Lisa Coutts said her love of "Mockingbird" made her buy "Watchman" — it’s the first hardback book she has ever purchased.

"’To Kill a Mockingbird’ is my favorite book of all time," said Coutts, 42. "I read it at school. It’s just a book I have to read during my holiday. I loved it and I thought, ‘Give it a go.’"

Lee, also known as Nelle, was expected to spend the day as she usually does at the 15-person assisted-living facility in Monroeville where she is closely guarded and only a short list of pre-approved visitors are allowed to see her.

Wayne Flynt, a historian and author, said he met with her on Monday and handed her an inch-thick stack of news articles and printouts about the release of "Watchman."

"She chortled," Flynt told The Associated Press on Tuesday. "She’s absolutely delighted. I think she’s a bit overwhelmed."

While Lee’s day is expected to be normal, "normal means monotonous and boring, except when you just took over the media of the entire world, in which case it’s a lot more exciting," he said.

Chandler reported from Monroeville. Associated Press Writer Ashley Chan in London contributed to this report.