In the late 1970s, Arthur Fleck, a struggling stand-up comedian, is trying to make ends meet by working as a clown for a children's hospital. He struggles to make his mother, Penny, proud, who has always been supportive of his aspirations. Despite his best efforts, Arthur remains stuck in a rut, unable to find success or happiness. As he navigates the dark alleys and decaying streets of Gotham City, Arthur's life becomes increasingly unravelled. His therapist, Dr. Munak, dismisses him as "a clown, not a real person" further eroding his already fragile sense of self-worth. Meanwhile, Arthur's mother is struggling with her own health issues, adding to the emotional turmoil. One day, while working at the hospital, Arthur's frustration boils over, and he snaps, killing three men who were bullying him. The incident sets off a chain reaction, propelling Arthur towards a path of destruction and chaos. As his alter ego, "Joker," emerges, Arthur becomes an infamous figure in Gotham City, known for his twisted sense of humor and unpredictable behavior. He starts to wreak havoc on the city, targeting those he perceives as corrupt or cruel. Throughout the film, Arthur's backstory is slowly revealed, showcasing the root causes of his descent into madness. His struggles with mental health, poverty, and neglect are all laid bare, providing a nuanced exploration of the Joker's motivations. As the story unfolds, Arthur's actions become increasingly erratic and disturbing, culminating in a violent rampage that leaves a trail of destruction in its wake. The film concludes with Arthur, now fully embracing his "Joker" persona, standing atop a pile of rubble, having achieved a twisted sense of freedom and liberation.