Rebecca Yarros has announced a new book in the Empyrean series, with some outlets reporting it is titled "Threshing Day" and others stating it is called "Peculiar Stars". The book is expected to be released, with one reported date being September 29. Details about the book's plot and title appear to be inconsistent across reports, with some indicating it is part of the Fourth Wing series and others suggesting it may not be the next book in the series.