Batman: Detective Comics Vol. 1: Mythology

Alfred Pennyworth...attacked at Wayne mansion! Who's hunting those closest to Batman? The monstrous shadow plaguing Gotham City gains the upper hand when two of the Dark Knight's most ardent allies fall prey to a violent vendetta! Commissioner Gordon calls in the Dark Knight Detective when there's a murder at the Gotham City Aquarium-staged to look exactly like Thomas and Martha Wayne's crime scene, right down to the playbill and pearls. How does this bizarre homicide tie into the shadowy monster that attacks Dr. Leslie Thompkins? This creature looks to wage a war on Batman-and it's using Joker Gas to do it! Collects Detective Comics #994-999