Onyx Storm is the third book in Rebecca Yarros's bestselling Empyrean fantasy romance series, following Fourth Wing and Iron Flame. Published by Red Tower Books (Entangled Publishing) on January 21, 2025, this hardcover novel spans 544 pages and continues the story of dragon rider Violet Sorrengail as she navigates war, politics, and romance at Basgiath War College and beyond.

The Empyrean series is planned to include five books total. Onyx Storm features an expanded world with new adventures across island kingdoms, political intrigue, and escalating battles against the venin threat. The story includes themes of loyalty, sacrifice, and forbidden magic, set in a richly imagined fantasy world of dragon riders and gryphon fliers.

Onyx Storm sold 2.7 million copies in its first week, making it the fastest-selling adult novel in 20 years according to BookScan. The book has been praised for its thrilling pace, emotional depth, and worldbuilding, and was a bestseller months before release due to pre-orders alone. ISBN: 978-1-64937-715-9.