Detective Comics, Vol. 1 #746 (2000)

Evolution, Part 4: Aftertaste
Batman has captured Mr. Abbot, Whisper A'Daire's monstrous henchman. But upon learning that the Detective is gaining ground, Whisper accelerates her plan. Using a refined version of her life-prolonging serum and the Galante mob's drug distribution, she plans to flood Gotham with this strange potion. But the side-affects could reduce Batman's city to a den of beasts.
Release Date: 2000