Described as "Not. A. Children's. Book", the new novel is set in the small British village of Pagford, and tells the story of what happens after the unexpected death of a town official leaves a vacancy on the town’s governing body.
Associated Press says "This is not a book that’s easy to fall in love with", and Rowling told The New Yorker:
"I thought I’d feel frightened at this point. Not just because it’s been five years, and anything I wrote after Potter—anything—was going to receive a certain degree of attention that is not entirely welcome, if I’m honest. It’s not the place I’m happiest or most comfortable, shall we say. So, for the first few years of writing ‘The Casual Vacancy,’ I kept saying to myself, ‘You’re very lucky. You can pay your bills, you don’t have to publish it."
The book touches on issues including drug addiction, poverty and self-harm - so it's more for an adult audience.
Released tomorrow, the book is already No. 2 on Amazon. Will it be able to match the success of the young wizard the world fell in love with?