Batman and Nightwing are forced to team with the Joker's sometimes-girlfriend Harley Quinn to stop a global threat brought about by Poison Ivy and Jason Woodrue, the Floronic Man.
As Batman hunts for the escaped Joker, the Clown Prince of Crime attacks the Gordon family to prove a diabolical point mirroring his own fall into madness.
Bruce Wayne is missing. Alfred covers for him while Nightwing and Robin patrol Gotham City in his stead and a new player, Batwoman, investigates Batman's disappearance.