We will be seeing the release of the second volume of Batman: Earth One by Geoff Johns and Gary Frank coming out shortly. The new graphic novel picks up six months after the last and there are a lot of questions about who Bruce Wayne is inside… and according to Johns when you have a lot of questions, you need The Riddler. So the villains for the second novel are The Riddler and a completely re-imagined Killer Croc. Johns also let slip that the third volume is already underway and will likely be released early next year.
Here is Johns talking to Tiffany Smith of DC All-Access