Eilish takes on the pivotal role of Esther Greenwood, the protagonist of Sylvia Plath's classic semi-autobiographical novel. The story delves into the journey of an aspiring young writer who lands a magazine internship in 1950s New York City, chronicling her profound struggles with ambition, identity, and mental health against the backdrop of restrictive societal expectations for women.

Production on the film has already concluded, with Polley, renowned for her work on "Women Talking," directing from her own adapted screenplay. She has curated an acclaimed supporting cast to complement Eilish, notably including Oscar and Emmy nominee Carey Mulligan, who Variety previously reported would portray Esther's mother, Mrs. Greenwood.

The newly confirmed additions to the cast feature Gotham Award winner Danielle Deadwyler as Dr. Nolan, Esther's psychiatrist; Actor Award winner Ike Barinholtz as Lenny, a wealthy New York City radio host; and "Heated Rivalry" breakout Connor Storrie as Marco, who becomes Esther's unfortunate blind date. The extensive ensemble also includes Dylan Hawco as Buddy Willard, Esther's first boyfriend; Lili Taylor as Jay Cee, editor of Ladies’ Day magazine; Ella Beatty as Joan, an old acquaintance who later shares a mental hospital stay with Esther; and Maggie Kuntz as Doreen, Esther's best friend and fellow intern in New York.

"The Bell Jar" is a co-production by Plan B, Studiocanal, and Joy Coalition. Focus Features is set to handle the distribution, with an official release date yet to be announced.