J.K. Rowling’s Harry Potter series might have dominated YA fantasy when it was first published, but there was another series of books that was received an equal amount of critical acclaim: Philip Pullman’s His Dark Materials trilogy. Ever since the last installment hit bookstores in 2000, Pullman has spoken about a “companion” novel to the trilogy, which he called The Book of Dust. Today, he announced that The Book of Dust isn’t one book; it’s three, and the first installment will hit bookstores on October 19th.

Pullman’s 1995 novel The Golden Compass was the first installment of the trilogy, and introduced readers to a young girl named Lyra Belacqua, who lives in an alternate world ruled by a theocracy called the Magisterium. After Lyra’s friends are kidnapped, she sets off to the arctic to rescue them, and discovers a sinister plot by the Magisterium that is linked to a mysterious particle known as Dust, which her uncle has been studying in secret.

A film based on Compass earned mediocre reviews in 2007, and in 2015 the BBC announced an eight-part television series based on the trilogy. The Subtle Knife and The Amber Spyglass rounded out the series, and Pullman wrote several additional stories that tied into the universe in the years after. In 2003, the author first announced that he was working on The Book of Dust, and he’s offered sporadic updates in the years since.

In an interview with NPR, Pullman noted that the first installment of The Book of Dust trilogy will be set prior to the events of The Golden Compass, when Lyra is an infant, while the second and third installments will take place a decade after the events of The Amber Spyglass. “It doesn’t stand before or after His Dark Materials, but beside it,” Pullman explained. “It’s a different story, but there are settings that readers of His Dark Materials will recognize and characters they’ve met before.” The trilogy will tell the larger story of struggle between the Magisterium and “those who believe thought and speech should be free.”

Pullman noted that he wanted to use the trilogy to explore the nature of Dust, which in the world of the books is essentially responsible for consciousness, and viewed by the Magisterium as the source of original sin. “That's what I really wanted to explore in this new work," he told NPR. "More about the nature of Dust, and consciousness, and what it means to be a human being."

Today’s announcement didn’t reveal the titles for the individual installments of the trilogy, and it’s not clear when the second or third installments will be released. Despite that, this is a long-overdue treat for fans of His Dark Materials.