Murder is no laughing matter in this savage, disturbing and extraordinary thriller.
And though it's a comic book superhero origin story for Batman's arch-enemy, Joker, it's definitely not for the kids.
Joaquin Phoenix stars as the uneducated, disenfranchised, self-pitying fantasist, Arthur Fleck, an aspiring stand-up comic and part time clown who lives with his mother.
Repeatedly ridiculed and failed by society, his sadness leads to anger, crime and civil unrest, and he achieves a degree of celebrity which brings meaning to his life.
A dirty, rotten and violent reflection of his increasingly tortured psyche, Gotham City is in desperate need of hope, but young Bruce Wayne has yet to create the Batman suit, and his arrogant father is very much alive and running for mayor.
Phoenix has always been a gloriously intense and uncompromising performer and here he achieves greatness with a mesmerising turn as Joker, which drags you kicking and screaming inside the worldview of a man as he goes violently insane.
A certainty to be up for the major awards, Phoenix makes Heath Ledger’s Oscar winning turn as Joker seems as mad and threatening as Cesar Romero’s pantomime version from the 1960’s Batman TV series.
Phoenix is so immersed in the character I was worried for the actor's sanity.
Classic films such as The King of Comedy and Taxi Driver are major influences with the star of those films, Robert DeNiro appearing here as a talk show host and is clearly in the joke.
DeNiro's taking part has the air of his passing to Phoenix the mantle of the greatest Hollywood actor working today.
And in losing over 3 stone in weight for the role, Phoenix demonstrates a dedication to his craft of which DeNiro would be proud.
Never afraid of offending his audience, director and writer Todd Phillips is best known for his bad taste Hangover films, and was Oscar-nominated for the screenplay for Sacha Baron Cohen's 2006 provocative satirical comedy film, Borat.
And this film is already proved controversial with Warner Bros. having to issue a statement denying the film endorses gun violence.
Phillips and Phoenix sat next to each other after my screening and were clearly enjoying each other's company as they discussed the movie, with Phillips described his film as a ‘deep dive character study’, and Phoenix called it ‘fresh, exciting and terrifying’.
And they’re not wrong.
As tragedy twists into comedy and back again you'll laugh even though you know you really shouldn't.
And despite being an extremely uncomfortable and stressful watch, I absolutely loved it.
