I went to this movie for two reasons: I enjoy psychological mysteries and thrillers and I love a good movie with fine acting. The movie did not disappoint because it had both.
At first I didn't want to go to "Joker" because I thought it was a movie about mass murder and/or endless violence.
Joker is about a sad man with an unfortunate laughing condition (he laughs at inappropriate times). He is also extremely dillusional. His mental illness is most likely schizophrenia.
He grows up in horrible circumstances. As an adult he is still living at home caring for his sick mother. He's trying hard to make a living as a children's clown.
He grew up with a single mom. Without spoiling the story, I'll just say his life as a baby, his childhood and upbringing was difficult. Now he's working as a children's clown to support his mother and himself. He gets bullied and knocked around by hoodlums on the street and subway. Even his counselor gives him the "bored, yeah well that's life treatment". It seems almost everyone is either outwardly aggressive, unkind, "laughing and poking fun at", or just plain trying to avoid a person who is different.
Many things go wrong and he spirals out of control. But, it's difficult to know what's happening in real life, and what's happening only in his mind. Sometimes the movie makes it clear, sometimes it doesn't.
*Outstanding acting