In an attempt to take down organized crime in Gotham, Batman goes to odds with the Joker

Rating: 10/10 (16 July 2017)

The oldest story in existence is that of good vs evil. Audiences to the story identify with the force of good which is only natural; the narrative practically always follows the "good guy" and people prefer to think of themselves as being inherently good. "The Dark Knight" (2008) explores the dichotomy of good and evil by keeping the traditional narrative, but challenging the way in which audiences identify with certain themes.
For as long as Batman and the Joker have been at odds, Batman has always represented truth, justice, and the force of good while the Joker has been an advocate for chaos and self-indulgent depravity. The two characters' motivations for their respective behaviors had always been overlooked by audiences until the release of "Batman: The Killing Joke" in 1988. In The Killing Joke, the Joker's origin story is revealed and he divulges that he commits atrocities to prove that deep down, everyone (even Batman) is just as immoral as he is, proclaiming that "all it takes is one bad day."
In The Dark Knight, the Joker sets out to prove that very same argument, which culminates with his plan involving the two ferries. Before the Joker's plan fails to come to fruition, audiences assume that Batman intends to prove that people are inherently good, but as the film nears its end, it becomes apparent that the true moral of the story is that people choose whether to be good or evil, something the Joker had anticipated and abused. The Joker takes advantage of Harvey Dent's grievous situation as his "ace in the hole," with hopes that the people of Gotham will become disheartened after seeing the most noble of people turned evil. In the end, to keep the Joker from winning over the minds of the people, Batman ascribes Dent's misdeeds to his own reputation to save Dent's, giving the people of Gotham an idol to rally behind.
Overall, the film's production, acting, and effects work in perfect rapport with its themes and narrative to achieve a perfect 10 in my opinion.