So which of those villains will be the primary face behind it all will be the mystery. The 6 villains will probably be interrogations, not characters with extensive back story and development. Basically, the universe exists, no need to rebuild the world.

Rumor has it that the story is inspired by (but not a direct adaptation) of the amazing The Long Halloween story line from the comics. That story is a year long investigation by Batman trying to get to the bottom of murders being committed on every major holiday. Most of his rogue's gallery was a suspect at some point in the story, while he narrows it down.