Go Set a Watchman may have met a cool reception from some critics, but readers have made it the hot book of the summer. Harper Lee’s second novel will likely end up being the top-selling book for 2015.

Barnes & Noble and Books-A-Million both reported that Watchman had the largest first-day sale of any adult fiction book in the history of both retailers. B&N noted that Watchman sales topped those of Dan Brown’s The Lost Symbol, which held the title of fastest first-day sales since its release in 2009. The book also knocked E.L. James’s Grey off the top of B&N’s bestsellers list, and the company expects that Watchman will be its biggest seller for the year. “Go Set a Watchman has proven to be one of the most exciting publishing events in our history,” said Mary Amicucci, v-p of adult trade and children’s books at B&N.

BAM’s CEO Terry Finley said Watchman sales were “beyond our most optimistic projections.” Finley said demand was strong nationally, and extremely strong in the Deep South. “We’ve already placed a substantial reorder with HarperCollins,” Finley said last Wednesday.

Amazon couldn’t provide new sales figures, but a spokesperson repeated the company’s earlier announcement that Watchman was the most preordered print title since the 2007 release of J.K. Rowling’s Harry Potter and the Deathly Hallows.

Left Bank Books in St. Louis was one of numerous independent booksellers that had strong first-day sales, selling 129 copies on day one, many of them preorders. Lori Fazio, general manager of RJ Julia Booksellers in Madison, Conn., said the release of Watchman made it “Christmas in July.” Sales remained strong on Wednesday and Thursday and, having sold more than 300 copies, Fazio said she has placed a substantial reorder.

Watchman sold 105,000 first-day copies in the U.K., but HarperCollins’s U.S. division declined to reveal first-day sales in the States.

The critical reception to Watchman was decidedly mixed. A number of critiques, including PW’s own review (see facing page), said it paled in comparison to Lee’s To Kill a Mockingbird. Others thought it was an important contribution to better understanding Mockingbird and to observing how Lee evolved as an author. Others praised Lee for adding new insights about racial attitudes in the South in the 1950s, when Watchman is set.