Carey Mulligan is reported to be joining the cast of “The Bell Jar,” a film project associated with Focus Features. Multiple outlets report that the movie will mark Billie Eilish’s acting debut. While at least one source says the studio has not formally announced the project, Variety reports that Mulligan will play Mrs. Greenwood. The available reporting frames Mulligan’s involvement as part of a new development in the film, with Eilish transitioning from music to acting for the first time. Deccan Chronicle also highlights Mulligan’s film credentials, noting her status as a three-time Oscar nominee, citing her performances in “An Education,” “Promising Young Woman,” and “Maestro.” Beyond casting, the sources provided do not include additional details such as release dates, directors, or plot specifics. The information currently centers on Mulligan’s reported role and the broader casting context of Eilish’s debut, with formal studio confirmation still not described in the excerpts.