The story unfolds in Gotham City during the tumultuous year of 1981. The central character, Arthur Fleck, portrayed by Joaquin Phoenix, works as a clown-for-hire at a company known as Ha-Ha's. Despite his job, Arthur grapples with profound depression, which he attempts to alleviate by performing and making others laugh. His daily life takes a tragic turn when he is tasked with promoting a store by dancing and waving a sign, only to have it snatched by a group of punk teens. In his futile attempt to retrieve it, he finds himself violently assaulted in an alleyway.
Amidst a backdrop of rampant crime, unemployment, and poverty in Gotham, Arthur relies on a social worker for his medication, reflecting a society deeply troubled. A seemingly innocent moment on a bus, where he tries to entertain a child, ends in embarrassment when the child's mother rebuffs him, highlighting his struggle for connection. His laughter, seen as inappropriate, is a symptom of his mental illness, a fact he tries to explain with a card.
Arthur returns to his dilapidated apartment, sharing space with his sickly mother, Penny, played by Frances Conroy. Evenings are spent watching Murray Franklin, the charming talk show host, played by Robert De Niro. During these moments, Arthur daydreams of captivating the audience, earning Murray's affection, and embracing his mother in front of everyone.
His co-worker, Randall, gifts Arthur a gun for protection after a recent mugging scare. Although apprehensive, he begins to feel empowered by this newfound tool, which stands in stark contrast to his boss’s unyielding reprimands. Meanwhile, Arthur finds himself drawn to his neighbor, Sophie Dumond, played by Zazie Beetz, who despite his awkwardness, seems to understand him on a personal level. Their budding relationship, fraught with Arthur's insecurities, leads him to invite her to his stand-up comedy performance.
As Arthur navigates the comedy scene, he feels increasingly out of place, overwhelmed by his condition that compels him to laugh excessively, making authentic comedy almost impossible. His attempts to cheer up sick children at a hospital take a dark turn when his gun accidentally slips from his pocket, resulting in severe consequences from his boss. The tipping point arrives when Arthur is attacked on a subway by three Wall Street men. Overcome by instinct, he defends himself, resulting in their brutal deaths, marking the pivotal change in his psyche.
In the aftermath, a strange sense of liberation washes over him as he dances in the restroom, embracing his identity as a clown – both literally and metaphorically. As the murders garner mixed reactions from the public, Arthur unwittingly becomes a symbol for the downtrodden, deepening his transformation into a character known as the Joker.
His quest for understanding leads him to discover troubling truths about his past, including his ties to Thomas Wayne, played by Brett Cullen, which Arthur learns may reveal his true lineage. Confronting Thomas leads to deeper feelings of betrayal and humiliation, ultimately culminating in tragedy. Arthur grapples with the realization of his mother’s abusive history, a revelation that forces him to take drastic action against her.
Following multiple events of violence, Arthur prepares for his appearance on Murray’s show, painting his face to symbolize his complete transformation. Faced with an increasingly hostile environment and reeling from a series of personal losses, Arthur’s moment on stage turns into an explosive confession, culminating in an unforeseen act of violence that shocks the audience and sends the city into chaos.
With Gotham descending into anarchy, Arthur finds exhilaration within the turmoil he has sowed, solidifying his position as a figurehead for rebellion. As his journey concludes, Arthur sits in an Arkham Asylum office, sharing a dark laugh with a new social worker, hinting at the cyclical nature of his existence. He leaves behind a trail of bloody footprints, a stark reminder of the chaos that surrounds him. The film captures a harrowing tale of a man pushed to the edge, exploring the fine line between madness and comedy.
