Is Threshing Day Fourth Wing Book 4? What It Is, When to Read It (2026)

BookBinge · 2026-10-07

Is Threshing Day Fourth Wing book 4?

Threshing Day isn't book 4: it's a companion collection of thirteen short stories about the day Basgiath cadets bond their dragons, published by Red Tower Books on September 29, 2026. The fourth Empyrean novel had no title or release date as of October 2026, and Rebecca Yarros started writing it in March 2026.

The short answer

Rebecca Yarros · 3 novels + Threshing Day

What it is: Thirteen short stories, each following one cadet through Threshing, the day dragons choose their riders. Out September 29, 2026.
When to read it: After Onyx Storm. The publisher says it's best read after book 3 because it contains spoilers.
Needed for book 4?: No. Yarros has said what the stories reveal will also turn up in book 4, in smaller ways.
Book 4: No title or date yet. Yarros began writing it in March 2026, and the series is planned at five novels.

Spoiler warning: this post names the thirteen cadets in Threshing Day and roughly when each story is set, which gives away small details from Fourth Wing and Iron Flame, such as who is in Violet's year and who arrives in book 2. It says nothing about what happens inside the stories and nothing about the plot of Onyx Storm. Nothing here guesses at book 4 beyond what Yarros and her publisher have announced.

The mix-up is easy to make. Threshing Day is the fourth Empyrean book to come out, and our Empyrean reading order lists it as the fourth entry, after Onyx Storm. That's its place in the reading order, not in the main story. The next novel about Violet and Xaden is still being written.

What Threshing Day is

Threshing is the day first-years in Basgiath's Riders Quadrant go into the valley and try to earn a dragon's bond. Each of the thirteen stories follows one cadet through their own Threshing. The publisher names them: Xaden Riorson, Rhiannon Matthias, Dain Aetos, Liam Mairi, Ridoc Gamlyn, Sawyer Henrick, Garrick Tavis, Imogen Cardulo, Bodhi Durran, Mira Sorrengail, Brennan Sorrengail, Aaric Graycastle and Sloane Mairi.

Violet doesn't get a story; readers already lived through her Threshing in Fourth Wing. When she announced the book in July 2026, Yarros called it "a fun trip back to Basgiath while I'm writing book four."

The first printing is a deluxe hardcover with sixteen full-color illustrations by Joe Requeza. The ebook has fifteen black-and-white illustrations, and the publisher lists it at 208 pages. US retailers list a standard hardcover with black-and-white art for October 13, 2026, at 224 pages. In the UK, Piatkus published it on the same day as the US edition.

When the stories are set

Every story takes place on a Threshing Day in the past, so the book doesn't pick up where Onyx Storm ends. Reviewers list the stories from oldest to newest. The collection opens with Brennan Sorrengail, Violet's older brother, years before Fourth Wing begins, and Mira's and Xaden's stories also come before Violet arrives at Basgiath.

Rhiannon, Sawyer, Ridoc and Liam went through Threshing in Violet's year, so their stories show the same day as Fourth Wing from their side. The last two belong to Sloane Mairi and Aaric Graycastle, first-years in Iron Flame. For Xaden, it's the first time readers see his Threshing through his own eyes.

Where it fits in the reading order

The publisher's own listing settles this. It says the Empyrean is best read in order, lists Fourth Wing, Iron Flame and Onyx Storm as books 1 to 3, and adds that Threshing Day can work as an introduction but is best read after Onyx Storm because it contains spoilers. Our reading order follows that: Fourth Wing, Iron Flame, Onyx Storm, then Threshing Day.

Because some stories happen years before Fourth Wing, a strict timeline order would break the book up and put parts of it first. We wouldn't do that. Reading in publication order keeps each reveal where Yarros put it, which is the usual argument for publication order over chronological order.

Threshing Day spoils all three novels

Expect spoilers for Fourth Wing, Iron Flame and Onyx Storm. The publisher flags them, and reviewers' spoiler warnings cover all three books. Even the cast list gives a little away, since two of the thirteen cadets don't arrive at Basgiath until Iron Flame.

If you're partway through Onyx Storm, finish it first. If you stopped after Fourth Wing, this isn't a way to catch up either. It fills in the side characters rather than recapping the main plot.

You don't need it before book 4

Threshing Day is optional. Around the release, Yarros said that what the stories reveal will also show up in book 4 in smaller ways, without a long look at each character. You won't be lost if you skip it.

Our suggestion: read it if you want more time with Rhiannon, Ridoc, Liam or the older riders, or if the wait for book 4 is dragging. Skip it if you read the Empyrean only for the main plot. At 224 pages in hardcover, it's a short commitment either way.

What's confirmed about book 4

Writing: In March 2026, Yarros posted an Instagram Reel saying she had started writing book 4, after sending a contemporary novel to her editor. When she announced Threshing Day in July 2026, she said again that she was writing book four.
Title and date: None announced as of October 7, 2026. Her site lists two upcoming releases, and neither is book 4: Peculiar Stars, a contemporary romance, on November 17, 2026, and volume 1 of the Fourth Wing graphic novel on April 6, 2027.
Plot: There's no official synopsis, so anything you read about book 4's story is a guess.

Treat any date you see on a retailer placeholder or in a screenshot as unofficial until Yarros or Red Tower Books announces it. For books that do have dates, see our new releases.

How many books the Empyrean will have

Five novels. Yarros told TODAY in June 2023 that the series was fully plotted for five books, and in January 2025 she said that how book 5 starts and how the series ends were already worked out. Threshing Day sits outside that count, which is why the next novel is still called book 4.

Keeping track of where you are

BookBinge is an iPhone app that keeps 333 series in reading order, the Empyrean among them, with Threshing Day after Onyx Storm. It remembers which book you're on, and its AI recap is written only from the books you've marked finished. It stops exactly where you stopped, so if you finished Iron Flame but not Onyx Storm, nothing from book 3 gets in.

It's free to start, with one free recap and up to three series active at once. Pro adds unlimited recaps and Release Radar, which sends a notification when a series you follow has a new book on the way. Pro is $24.99 a year with a 3-day free trial, or $3.99 a week.

Frequently asked questions

Is Threshing Day book 4 of the Empyrean series?

No. It's a collection of thirteen short stories about Threshing, published by Red Tower Books on September 29, 2026. The fourth Empyrean novel is a separate book that hasn't been titled or dated yet.

Do I need to read Threshing Day before Fourth Wing book 4?

No. Yarros has said what the stories reveal will also show up in book 4 in smaller ways, so it's optional. Read it if you want more time with side characters like Rhiannon, Liam and Brennan.

When should I read Threshing Day in the Fourth Wing reading order?

After Onyx Storm. The publisher says it can work as an introduction but is best read after book 3 because it contains spoilers.

When is Fourth Wing book 4 coming out?

No date had been announced as of October 2026. Yarros started writing it in March 2026, and her next dated releases are Peculiar Stars on November 17, 2026 and volume 1 of the Fourth Wing graphic novel on April 6, 2027.

How many books will be in the Empyrean series?

Five novels. Yarros told TODAY in 2023 that the series was plotted for five books, and in January 2025 said book 5 and the ending were already plotted. Threshing Day is a companion and sits outside that count.

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