A man with mental troubles, including pathological laughter, receives blow after blow from life/society, and this causes irreversible changes. The person in question is the one we all know as Arthur Fleck/Joker and we witness how he slowly but completely transforms his belief system.
The film is particularly well made, more surprisingly so considering the genre (based on comics) and the director's switch from making more or less successful comedies (The Hangover, Road Trip and others). If the character's identity was not in the title and in the minds of everyone long before it was released, the fans of the movie would be mostly of a different type. In fact, I wish the producers had done that.
It is a purely artistic film, and Mubi would be happy to host it. It presents a (very) slow process of decomposing/recomposing the Joker's mental component and the complete transposition of his personal indicator for what is good or bad and what are the right actions for each choice. The music acts like a silent witness of this transformation, enhancing the actor's expressiveness, accompanying him tirelessly and effectively and punctuating all the significant moments.
Joaquin Phoenix is magnificent and magnetic in Joker's skin, something that shouldn't surprise anyone by now. Towards the end, you will feel guilty for the number of times you'd still be rooting for him, even as he commits repulsive acts.
There is an element of the story that I didn't like, but it pales in comparison to the full effect of the film, and for the sake of avoiding spoilers, I won't mention it. It involves manipulating the public's perception of the facts for a cheap-ish effect, but only for a brief moment really.
Screenplay: Todd Phillips, Scott Silver
Directed by: Todd Phillips
With: Joaquin Phoenix, Frances Conroy, Robert De Niro, Zazie Betz, Shea Whigham