The second movie in Christopher Nolan's Batman Trilogy.
The sequel to Batman Begins and continuing the story about 6 months after, The Dark Knight tells the tale of Bruce Wayne's dealings with his most infamous villian yet, The Joker. Also during the tale of the movie, we witness Batman's dealing with the crazed Two-Face, who combined with the Joker, forces Gotham and Batman to question themselves to their core.
This movie has become one of the top grossing movies of all time due to its high critical reception and because of the death of one of the main stars, Heath Ledger, who played the Joker.
Wikipedia Page: The Dark Knight