No specific fan theory is identified as officially confirmed in the available reporting. Rebecca Yarros’s Threshing Day is a collection of Empyrean stories, not the next main-series novel. The sources reviewed describe the book and separate it from Book 4, but do not substantiate the headline’s claim that the collection confirms a particular theory.
What is Threshing Day?
Yarros’s Threshing Day page describes “Thirteen unforgettable stories. One Legendary Day.” Publishers Lunch, reporting on the author’s Instagram announcement, quoted her describing it as “thirteen threshing stories about some of your favorite characters and their dragons.”
| # | Preview | Product | Price | |
|---|---|---|---|---|
| 1 |
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Fourth Wing | $11.80 | Buy on Amazon |
| 2 |
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Threshing Day (Wing and Claw Collection) (The Empyrean) | Buy on Amazon | |
| 3 |
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Fourth Wing | $16.91 | Buy on Amazon |
| 4 |
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Fourth Wing Series 3 Book Set | $55.99 | Buy on Amazon |
| 5 |
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Iron Flame (The Empyrean, 2) | $11.87 | Buy on Amazon |
USA Today reported that the book was scheduled for release on September 29, 2026, and that its deluxe first edition includes 16 original illustrations by Joe Requeza. Yarros’s site now labels the book available. Retailer inventory, formats, and editions can vary, so check the current listing for the version you want.
Is it the next main-series book?
No. In the announcement quoted by Publishers Lunch, Yarros said, “I hope this gives you a fun trip back to Basgiath while I’m writing book four!” That wording distinguishes the collection from Book 4. Readers looking for the continuation after Onyx Storm should not treat Threshing Day as that next installment.
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Publishers Lunch’s announcement report establishes the collection’s format and Yarros’s comment that she was writing Book 4; it does not identify a theory confirmed by a story in the collection.
What did Yarros say about Ridoc?
In its account of a Fourth Wing Night Q&A with the New York Mets, Brit + Co reported Yarros saying of Ridoc, “I can tell you that right now as I am writing book 4, he is still currently among us.” The report also says she was plotting Book 5 alongside Book 4. These are reported comments about the character’s status during the writing of Book 4 and her planning; they are not evidence that Threshing Day confirms a named fan theory.
Brit + Co’s event coverage is the source for those remarks. They should be understood as attributed reporting from the Q&A, not as a passage from the new collection.
What can readers conclude about the theory claim?
A claim that an author officially confirmed a theory needs to identify the theory and point to an explicit author statement or book passage that supports it. The available reports do neither for Threshing Day. That does not prove no story could prompt readers to interpret events in a particular way; it means the specific official confirmation implied by the headline is not established by these sources.
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Coverage of the series also notes that concrete plot information about Book 4 has been limited. Marie Claire’s Empyrean series guide recounts earlier remarks and unresolved questions, but those are separate from evidence of a theory being confirmed in this collection.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which book should you read next?
- For additional Empyrean stories: choose Threshing Day, the thirteen-story collection.
- For the main plot to continue: wait for Book 4; Yarros’s announcement described Threshing Day as a return to Basgiath while she was writing that novel.
For current availability and editions, start with Yarros’s official book page and confirm format and stock with the retailer before ordering.
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