The Dark Knight Returns.

Without getting into specifics, the key thing that makes the third film a great possibility for us is that we want to finish our story, and in viewing it as the finishing of a story rather than infinitely blowing up the balloon and expanding the story. We have a great ensemble, that’s one of the attractions of doing another film, since we’ve been having a great time for years.Christopher Nolan discusses Batman and Superman (but no World’s Finest)