HBO's long-awaited third season of Big Little Lies has moved a step closer to production with news that author Liane Moriarty is releasing a sequel novel, Big Little Truths, on 25 August. The book, Moriarty's first-ever sequel, picks up with the "Monterey Five" a decade after the original story and will serve as the source material for the new season, which has been in development for more than five years. HBO is understood to have been waiting for Moriarty to finish the novel before progressing the show in earnest, underlining how closely the television adaptation depends on her original writing.

Big Little Truths centres on the same close-knit group of mothers, now navigating their children's teenage years, when a mysterious stranger appears near the local high school and the school principal receives a severed human finger in the post, dredging up long-buried secrets. The article also traces the unusually close creative relationship between the books and the TV series: Moriarty wrote an unpublished novella to shape season two, introducing Meryl Streep's character Mary Louise Wright, while Laura Dern's acclaimed portrayal of Renata Klein has, in turn, influenced the character's expanded role in the new novel, illustrating a two-way exchange between page and screen.