Published five years after the release of the last book in the boy wizard saga, The Casual Vacancy is already at No. 1 on Amazon’s U.S. chart, and bookmaker William Hill put 2/1 odds on it outselling “Harry Potter and the Deathly Hallows,” which shifted 2.6 million copies in Britain on its first day.

Many of the early buyers were Harry Potter fans who, like the author, have moved on to more adult fare.

“I just like how much excitement there is about a book,” said 23-year-old Grace Proctor, a “massive” Potter fan who was first to buy the book at one London store.

“I think there are going to be people who will hate it just because they can hate it,” she said. “But she’s such an amazing writer, I don’t think she can go wrong.”

A story of ambition and rivalry set in the fictional English village of Pagford, the novel recounts the civic warfare sparked when the unexpected death of a town official leaves a vacancy on the governing body.

Rowling has said she was aiming for Dickensian sweep in the multi-character saga, whose doses of sex, satire and swearing mark a distinct departure from wholesome Harry.

Reviews have been mixed. The Associated Press judged it a challenging but rewarding read full of emotion and heart, while The Guardian newspaper said it was “no masterpiece, but it’s not bad at all- intelligent, workmanlike, and often funny.” Several reviewers felt the lack of easily likable characters might be off-putting to readers.

It’s likely nothing Rowling publishes will ever match the success of the Potter books, which have sold more than 450 million copies around the world.

But booksellers are confident The Casual Vacancy will be one of the year’s best-sellers, whatever reviewers say.

“A lot of children have grown up with Harry Potter. They’re now adults who love books,” said Susan Sinclair, divisional manager for the Foyles bookstore chain.

“I think it’s going to be a really big seller at Christmas. It’ll be an easy gift but also a good one.”