After a climactic struggle in the Batcave, Two-Face is betrayed by the Joker, who shoots at Dent, causing him to fall into a chasm, presumably to his death. Batman admits in the aftermath that, even if Two-Face has survived, Harvey Dent is gone forever.

Why did Two-Face became evil?

Boss Sal Maroni throws acid at Harvey, scarring half of his face. ... He became obsessed with duality and opposites, and developed a second persona, the villainous Two-Face, to compliment the law & order obsessed Dent.

What happened to Two-Face in Dark Knight Returns?

He aired a broadcast demanding a ransom, his face wrapped in bandages. His actual plan was to be on the tower when it blew up and killing himself. Batman intervened and Two-Face and his goons flew away in a helicopter. Batman pulled Harvey from it and saved him from falling to his death.