The Fourth Wing author revealed the two things fans should look for in Onyx Storm for a big hint about one character's fate in book four

Little moments in Rebecca Yarros' bestselling fantasy novel "Onyx Storm" could have huge implications for the rest of her "Empyrean" series.

The book, the third in a series, has sold 2.7 million copies in its first week, and provided yet another example of the romantasy genre’s staying power.

“Onyx Storm,” the much-anticipated and latest book in Rebecca Yarros’ best-selling series, “Fourth Wing,” has taken the world by storm.

Rebecca Yarros’s ‘Onyx Storm is the fastest-selling adult novel in the past 20 years. The book, the third in a series, has sold 2.7 million copies in its first week and is topping every bestseller list.

Bookshop manager Edward Woods refused to disclose how many copies had been sold in Romsey but said it had performed very well.

Rebecca Yarros released "Onyx Storm" on January 21, but readers are already looking forward to the next book in the "Fourth Wing" universe.