The Dark Knight ending explained

What happens

Harvey Dent, broken by Rachel's death, becomes Two-Face and falls to his death while threatening Gordon's family. Batman takes the blame for Dent's crimes so Gotham keeps believing in him, and he vanishes, hunted.

The last image

Batman disappears into the night while Gordon destroys the Bat-Signal, and the city he saved sets out to hunt him.

What it says

Gotham needs a hero it can believe in more than it needs the truth. Batman accepts being hated so Dent's image stays clean, which makes his victory a sacrifice and the ending a bleak argument for protective myth.