The official synopsis for the upcoming Joker solo film promises that the story will be a cautionary tale of sorts.

The film is being directed by Todd Phillips (War Dogs), and seeks to explore the early days of the Joker, outside of his long-standing antagonism with Batman. The film will not feature Bruce Wayne as a Dark Knight, but will instead showcase a Gotham City with a grimy edge to it before Batman ever appeared.

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Earlier reports and the new synopsis reveal that Joaquin Phoenix will play a struggling comedian named Arthur Fleck who goes off the deep end and becomes the Joker. The film is also reportedly similar to The King of Comedy, a dark comedy from Martin Scorsese that starred Robert De Niro. De Niro is set to appear in Joker, supposedly as a late-show comedy host, with Marc Maron acting as the booking agent for his comedy show.

Check out the full synopsis below:

“Joker” centers around the iconic arch-nemesis and is an original, standalone story not seen before on the big screen. The exploration of Arthur Fleck (Joaquin Phoenix), a man disregarded by society, is not only a gritty character study, but also a broader cautionary tale.

Directed and co-written by Phillips, Joker stars Joaquin Phoenix as the titular character along with Robert De Niro, Marc Maron, Zazie Beetz, Frances Conroy, Brett Cullen and Bill Camp. It is scheduled to be released on Oct. 4, 2019.