Read the three numbered Empyrean novels in this order:
Fourth Wing, Iron Flame and Onyx Storm are Books 1–3. Threshing Day is a separate Empyrean companion collection, not Book 4.
After Onyx Storm, add Threshing Day if you want the optional companion stories.
Sources: Rebecca Yarros — Fourth Wing, Rebecca Yarros — Iron Flame, Rebecca Yarros — Onyx Storm, Rebecca Yarros — Threshing Day · Verified Sep 14, 2026
Official sources number the novels 1–3. Threshing Day is a companion collection. We list it after Onyx Storm; that is our placement, not a publisher Book 4.
Sources: Rebecca Yarros — Fourth Wing, Rebecca Yarros — Iron Flame, Rebecca Yarros — Onyx Storm, Threshing Day — official companion collection site
The three numbered Empyrean novels in order.
Empyrean Book 2.
Empyrean Book 3.
Short answers, with sources.
Read Fourth Wing, then Iron Flame, then Onyx Storm. Rebecca Yarros’s official book pages identify them as Empyrean Books 1, 2 and 3.
Sources: Rebecca Yarros — Fourth Wing, Rebecca Yarros — Iron Flame, Rebecca Yarros — Onyx Storm
No. Yarros’s site classifies it as an Empyrean Secret Project, and the official Threshing Day site calls it a thirteen-story companion collection rather than the continuation of Violet and Xaden after Onyx Storm. Shelf of Worlds therefore keeps it outside the numbered series sequence.
Sources: Rebecca Yarros — Onyx Storm, Rebecca Yarros — Threshing Day, Threshing Day — official companion collection site
For a first read, Shelf of Worlds places Threshing Day after Onyx Storm. This is an editorial placement, not a publisher-numbered position: official sources describe it as a separate companion collection rather than Book 4.
Sources: Rebecca Yarros — Onyx Storm, Rebecca Yarros — Threshing Day, Threshing Day — official companion collection site
These sources support the reading order and important details about the books and their editions.