Behemoth! is the upcoming drama film that marks Tony Gilroy's return to the director's chair. He has written the screenplay and has also produced it with John Gilroy and Sanne Wohlenberg. Here's the official synopsis as per IMDb:"Follows a musician from a family of musicians who returns to Los Angeles. A love letter to the music of the movies and the people who make it."In recent news about the drama film, it has been reported that Will Arnett has joined the film's cast. This update has come just a day after news of David Harbour leaving the project. So let's get into the details of this piece of news.Will Arnett joins the cast of Behemoth!According to Deadline, Will Arnett has joined the cast of the upcoming film Behemoth! This update comes just a day after David Harbour's exit from the film. His departure reportedly stems from exhaustion after wrapping up Stranger Things. The Netflix series recently came to an end after nearly a decade of run. Arnett has replaced Harbour for an important role in the film. He has been part of titles including BoJack Horseman, The Lego Movie, and Arrested Development.Pedro Pascal plays the role of Alex Serian in the film. Other cast members include Eva Victor, Olivia Wilde, Matthew Lillard, Alexa Swinton, Margarita Levieva, and Barry Livingston. Behemoth! is shot by Damián García while John Gilroy is the editor. The production began in October last year in Los Angeles.It's Gilroy's first directorial venture since 2012's The Bourne Legacy. He has since written films including Nightcrawler and Rogue One, among others. In a June 2025 interview with The Playlist, Gilroy spoke briefly about his forthcoming film. He said that it's about the film's music.“I’m dying to make this movie. It’s a movie about movie music. It’s a movie about scoring [movies].”He said that the film is about a child prodigy who comes from a family of musicians. He returns to Los Angeles and starts his career.“The whole movie is surfing on music. And you find out through the flashbacks why he left [L.A.]. ‘Behemoth!’ is the fake name of this huge movie at the end. It has to shoot in L.A. and feature live musicians. It’s very expensive, but a lot of people want to help because it’s shooting in L.A., which is a coral reef about to die.”The storyline has a personal connection to Gilroy, who started out as a musician. He wanted to be a guitarist but eventually became a screenwriter. Just like his film's protagonist, Gilroy also comes from a family of playwrights.“I’ve been obsessed with movie music since they let me have a hand in it. So I’m really into this. [However], it’s very financially difficult; we’re way more expensive than one would hope, so that’s the trick, but I’m still hopeful and’d love to make it.”Searchlight Pictures is distributing the film. The makers are yet to reveal more details about the film's release date.Stay tuned to Soap Central for more such stories.