Rebecca Yarros’ latest novel is officially a blockbuster.

The romantasy author’s Onyx Storm, the third installment in her Empyrean series, has sold more quickly than any other adult fiction book in two decades, the New York Times reports.

The novel, published last week by Entangled, follows Violet, a student at a war college who embarks on a quest to recruit allies in the war against an army of invading “dark wielders.” A critic for Kirkus wrote of the book, “Given the hefty page count, it’s hard to understand why there wasn’t room for genuine character development or more than a gesture toward worldbuilding.”

During its first week on sale, Onyx Storm sold more than 2.7 million copies, according to the Times. As of Friday morning, the novel was the No. 1 bestselling book on Barnes & Noble’s website; its standard edition was the No. 10 bestselling book on Amazon, with a deluxe limited edition at No. 23. The first two books in the Empyrean series, Fourth Wing and Iron Flame, were also on bestseller lists from both retailers.

The book’s robust sales do not come as a surprise. Fourth Wing became a hit on TikTok after its 2023 publication, sending it to the No. 1 spot on the New York Times bestseller list; Iron Flame followed suit later that year.

On Instagram, Yarros reacted to Onyx Storm’s record-breaking sales with a post that read, “Astounded and so very grateful. Thank you!”

Michael Schaub is a contributing writer.