Though Batman and Batman Returns loom large over comic-book cinema history, Michael Keaton ended his run as the DC hero with untapped potential. Luckily, author John Jackson Miller was hired to imagine “what if?” His next book, Batman: Revolution, debuts The Riddler. Instead, his Burtonverse Riddler strikes a balance between theatricality and practicality. As was the case in Resurrection, Miller promises that The Riddler is only a piece of the puzzle in Revolution. “And as we'll see in Revolution, The Riddler isn't the only one.”Batman: Revolution arrives to bookstores on Oct. 21.