Bruce Wayne/Batman is on a spree of eliminating crime in Gotham City . To his help and rescue there are Lt. Jim Gordon (Gary Oldman) and District Attorney Harvey Dent (Aaron Eckhart).
Having done enough The Dark Knight wants to come out of the sinful organized crime for good and be free of their corruption. However to the surprise of all Batman finds that a new criminal who is also a psychopath mastermind the crimes . He is known as Joker (Heath Ledger) and has taken over organized crime.
In his pursuit to survive in the crime market , the Joker is killing those who is on a chase to find him off one by one. The story moves like this "The Joker's plan is to terrify the citizens and throw the city into chaos, and then kill Batman. Batman takes the fight with the Joker personal, which makes him confront his own beliefs. The Joker is the most dangerous criminal that Batman has encountered, and he will need all his strength and vigilance to defeat him."