'Threshing Day' answers questions 'Fourth Wing' fans have about Rebecca Yarros' series. Here's what you might've missed.

"Threshing Day" is the latest book in the "Fourth Wing" universe. Casey Paul/MLB Photos via Getty Images/Red Tower Rebecca Yarros released "Threshing Day" on Tuesday. The book unveils new lore about dragons and their riders from the "Empyrean" series. It also hints at romances developing in future "Fourth Wing" books. Happy Threshing Day! OK, it's not actually Threshing Day, but Tuesday is the day Rebecca Yarros released her new "Fourth Wing" book titled "Threshing Day." No, it's not book four in the "Empyrean" series, which readers have been anxiously awaiting since "Onyx Storm" was released in 2025. It's a collection of the stories of riders from the "Fourth Wing" universe on their Threshing Days, when they bond with their dragons in their first year of training at Basgiath War College. Protagonist Violet Sorrengail doesn't have a story in the collection, as her Threshing Day appeared in "Fourth Wing." Instead, Yarros offers the perspectives of people around Violet, unveiling new lore about the riders and their dragons. The stories have major ramifications for Yarros' beloved romantasy series, including how dragons bond and hints at future romances. Here are some of the most important details you might have missed in "Threshing Day." Multiple points of view The new book includes the story of 13 Threshings, though some of those stories take place on the same day. For instance, Xaden Riorson and Garrick Tavis experience Threshing Day together, and their chapters follow the day from their respective perspectives. Notably, Yarros includes a note at the top of the book that says, "The following text has been faithfully transcribed from Navarrian into the modern language by Colonel Valin Kaori and Lieutenant Ellery Mynna, professors of Dragonkind at Basgiath War College." "Threshing Day" by Rebecca Yarros. Red Tower That note differs from those included at the start of the "Fourth Wing" novels, which are transcribed by the scribe Jesinia Neilwart. Scribes have been revealed to be unreliable narrators throughout the events of the "Empyrean" series, while Dragonkind professors have not, making "Threshing Day" more trustworthy than other books in the series. Yarros confirmed at a book release event in Denver that readers can trust the narration in "Threshing Day," unlike in the rest of her series. "It tells you that yes, this is a faithful first POV," she said. "You guys can trust what happens in this book." How Threshing works Although readers saw Violet bond her dragons, Tairn and Andarna, in "Fourth Wing," much about the actual process remained a mystery. "Threshing Day" broke down how the process works in more detail. First, several of the riders describe feeling a tugging in their chests that leads them to their dragons, as if they are calling to them. Each rider also sheds blood during Threshing. Some scratch themselves on trees or get in a fight before they bond, but in Ridoc Gamlyn's case, blood seemed to appear out of nowhere: "I note a twinge in my knee that, yep, is bleeding. Huh. I must have landed on a twig or something back there." Yarros doesn't explain why each rider bleeds during their Threshing, but dragons frequently refer to bloodlines as sources of power in the "Empyrean" series. Several of the riders also express a need or desire before bonding, which is later fulfilled by the signet power they develop. Brennan Sorrengail thinks to himself how important menders are moments before he bonds his dragon and goes on to become a powerful mender. Imogen Cardulo wishes she could take back something she said, and then develops the power to erase memories (more on that later). The correlation suggests that signet powers align with a rider's temperament or desires, though we'll have to see how Yarros explores that concept down the line. Rebel dragons Many of the riders featured in "Threshing Day" are children of rebels who fought against Navarre, whom readers learned in "Iron Flame" and "Onyx Storm" are secretly bonding with dragons that previously bonded with their direct family members. The practice is forbidden in Navarre because it can allow riders to develop multiple signets, creating a power imbalance. In the first chapter of "Threshing Day," Professor Colonel Thadeus Palme reveals that even the staff struggles to tell dragons apart, creating the potential for confusion. There are three novels in the "Empyrean" series to date. Red Tower "I have found that no artist has flawlessly depicted every distinguishing mark of a dragon, which makes telling descendants apart woefully difficult," he wrote. "When in doubt, it is prudent to ask a cadet for the name of their dragon." Because humans rely on riders to trace dragons, the dragons can hide their identities. For instance, Imogen bonds with Glane, who is recorded as being 19 and having never bonded with a rider before her. Yet, Imogen knows that isn't true because she met Glane as a child when she was bonded to her grandmother. Garrick's dragon als