Novelist and TikTok phenomenon Colleen Hoover’s latest book sold more than 800,000 copies through the first day it went on sale, publisher Atria announced in a news release.

Hoover’s It Starts With Us, the sequel to her bestselling 2016 novel, It Ends With Us, set a fiction sales record for Atria. The figure reflects pre-sales—it was the most preordered book in the history of Simon & Schuster—as well as first-day sales of print, audio, and e-book copies of the novel.

Hoover’s latest novel follows a divorced florist whose jealous ex-husband becomes resentful when she begins seeing an old childhood friend. A critic for Kirkus wrote of the book, “Through palpable tension balanced with glimmers of hope, Hoover beautifully captures the heartbreak and joy of starting over.”

The author’s It Ends With Us was the novel that launched Hoover—already a bestselling novelist at the time—to fame on TikTok, the video sharing service that helped make her one of the world’s most popular authors.

In an interview with Kirkus, Hoover reflected on her sudden rise to TikTok fame.

Surreal is the only way I can describe it,” she said. “I’ve actually had to refrain from getting online much this year. The attention triggers my anxieties, so while I absolutely love it when friends and family send me fun videos about my books, I definitely don’t go searching it out.”

Atria and Grand Central Publishing recently announced that Hoover will be writing five new books for the two publishers. The first, a suspense novel, is scheduled for publication next year, with a romance coming in 2024.

Michael Schaub, a journalist and regular contributor to NPR, lives near Austin, Texas.