Which J.K. Rowling novel was her first adult fiction book?

The Casual Vacancy was J.K. Rowling’s first adult fiction book.

Published by Little, Brown in 2012, the novel is set in the fictional English town of Pagford. Its plot begins after the unexpected death of parish councillor Barry Fairbrother, leaving a vacant seat on the local council. The resulting election exposes conflicts involving class, poverty, addiction, family, and community responsibility.

The book differs sharply in tone and subject from Rowling’s children’s fantasy novels. It is a realist novel with an adult cast and no magical setting. It was also adapted into a three-part television miniseries by the BBC and HBO in 2015. Readers sometimes confuse it with The Cuckoo’s Calling, which was Rowling’s first novel written under the Robert Galbraith pseudonym, not her first adult novel overall.