Batman raises the stakes in his war on crime. With the help of Lieutenant Jim Gordon and District Attorney Harvey Dent, Batman sets out to dismantle the remaining criminal organizations that plague the city streets. The partnership proves to be effective, but they soon find themselves prey to a reign of chaos unleashed by a rising criminal mastermind known to the terrified citizens of Gotham as The Joker.
Set within a year after the events of Batman Begins, Batman, Lieutenant James Gordon, and new district attorney Harvey Dent successfully begin to round up the criminals that plague Gotham City until a mysterious and sadistic criminal mastermind known only as the Joker appears in Gotham, creating a new wave of chaos. Batman's struggle against the Joker becomes deeply personal, forcing him to "confront everything he believes" and improve his technology to stop him. A love triangle develops between Bruce Wayne, Dent and Rachel Dawes.
In The Dark Knight, the Joker is depicted as a maniacal criminal mastermind who terrorizes Gotham City and whose goal is to plunge it into anarchy.
The Joker has been described as a "psychopathic, mass murdering, schizophrenic clown with zero empathy." He was portrayed by the late Heath Ledger, in the role that won him a posthumous Academy Award for Best Supporting Actor.