Batman: Abyss (2013)

It's a new Gotham. Tim Drake is dead. Harvey Dent is cured. The Joker is curiously content in Arkham. Batman has exiled himself from Bruce Wayne. The Riddler and Scarecrow have formed an alliance that threatens to unearth the darkest of secrets forcing the Dark Knight to enlist The Question to answer the steepest of questions. What is the last riddle?