Harry Potter author JK Rowling will discuss her new book, The Casual Vacancy, in a BBC Culture Show special on the eve of its publication and the novel is said to include themes that will shock her fans.

The Casual Vacancy, published on September 27, is Rowling’s first novel for adults and it is set in the idyllic fictional English town of Pagford. It concerns the aftermath of the death of parish councillor Barry Fairbrother and the tensions that gather around the ensuing local election.

In JK Rowling – Writing for Adults which is broadcast on BBC Two on September 26, interviewer James Runcie meets the notoriously private writer in her hometown of Edinburgh to find out about the pressure and pitfalls of following up the 20th Century’s biggest literary phenomenon.

Runice has said that the new book will reveal unseen facets of the writer that will shock many of her fans. In the interview, Rowling reveals how she finally moved on from Potter and the challenges of making the leap writing fiction for adults.

In the interview she finally reveals the exact nature of the novel, with exclusive readings and in-depth discussion about its ideas, characters and inspiration.

Rowling has sold 450 million copies of the Potter books and has not published any new novels since Harry signed off with The Deathly Hallows in 2007. She has confirmed that there will be no more adventures about the world’s favourite wizard.