Rebecca Yarros is working on the 4th 'Empyrean' novel. Here's everything the 'Fourth Wing' author has said about the book so far.

Source: Business Insider

Rebecca Yarros released "Onyx Storm" in January 2025. Red Tower/CJ Rivera/Invision/AP"Onyx Storm" by Rebecca Yarros was published in January 2025. Yarros indicated in an Instagram post that she's starting work on book four of the "Empyrean" series.