“A Discovery of Witches” will be turned into a TV series. Penguin Books/

Another best-selling book is headed to the small screen. “A Discovery of Witches,” the first novel in Deborah Harkness’ “All Souls Trilogy,” will be adapted for TV, and the author will play a big role in the series.

Deadline, which reported the news, said Harkness will write “several episodes” of the historical fantasy series. Screenwriter Ashley Pharoah will also work on the series, which will be produced by “Torchwood” executive producer Jane Tranter and her company, Bad Wolf.

“A Discovery of Witches,” which celebrated its fifth anniversary of publication Tuesday, follows Diana Bishop, a witch who has ignored her powers. Her discovery of a magical manuscript leads her on an adventure in which she meets Matthew Clairmont, a 1,500-year-old vampire who falls in love with her. The series has sold over 3.5 million copies.

Harkness, who is also a history professor, expressed her excitement about the series on Facebook. “Jane and Ashley represent my dream team for bringing the trilogy to life,” Harkness wrote. “Every conversation we have had about the books shows how thoroughly they understand the All Souls World and how deeply they’re committed to creating something very special with this series. A glance at the projects they’ve been involved with — including the reboot of ‘Dr. Who,’ ‘Life on Mars,’ ‘Case Histories,’ ‘Waking the Dead,’ ‘MI5’/‘Spooks,’ ‘Torchwood,’ ‘David Copperfield,’ ‘Silent Witness,’ ‘Ashes to Ashes,’ ‘The Way We Live Now,’ and ‘Rome’ — makes it clear that Jane and Ashley are drawn to compelling characters and storylines with twists that keep viewers tuning in for each new episode.”

The “Discovery of Witches” writer will also serve as an executive producer. Her involvement in the series is good news for fans of the books. Often, writers are excluded from adaptations of their best-selling novels. However, the series that do involve the original authors, such as “Outlander” and “Game of Thrones,” tend to please audiences.

Harkness’ readers are hoping to actually see this adaptation on screen. Warner Bros. owns the movie rights, but they don’t seem to be making progress on the film version. The TV show was previously in development at the BBC and was eventually dropped. Bad Wolf’s version still isn’t guaranteed to hit the small screen. The “Discovery of Witches” TV show doesn’t have a network yet nor have any actors been cast, but the new writing and production team is certainly a step in the right direction.