A prequel to “It” is in development at HBO MaxVariety has learned from sources.

The series, currently called “Welcome to Derry,” will begin in the 1960s in the time leading up to the events of “It: Part One,” the 2017 film based on the Stephen King horror novel. The story is also said to include the origin story of Pennywise the Clown.

Andy Muschietti, who directed “It: Part One” and 2019’s “It: Part Two,” is attached to executive produce the series along with Barbara Muschietti and Jason Fuchs. According to sources, the Muschiettis and Fuchs developed the story for the show with Fuchs writing the script. Andy would also direct the first episode should the project go to series. the  A writers’ room is now open. Warner Bros. Television is the studio behind the project, with WB having produced the two films.

Reps for HBO Max and WBTV declined to comment.

Should the project go forward, it would be the latest example of HBO Max building a series component into an existing WB film franchise. Colin Farrell is set to reprise the role of The Penguin from “The Batman” in a limited series for the streamer, although a planned series about the Gotham PD (and Arkham Asylum) has stalled in development. There is also a series about the Bene Gesserit from “Dune” in the works at the streamer, among several other film-based projects.

The two new “It” films collectively grossed over $1.1 billion at the global box office upon their release, with the second film taking place 27 years after the events of the first with a new adult cast taking over from the kids in part one. “It” was previously adapted into a two-part miniseries for ABC back in 1990, featuring Tim Curry’s iconic performance as Pennywise.

The Ankler first reported the series was in the works.