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

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.