Set after the events of Justice League II, Batman is now investigating a series of crimes and robberies instigated by an unknown crook who has the ability to change his or her face. It turns out that this is actor Basil Karlo who, after being permanently disfigured, is doing errands for corrupt businessman Roland Daggett and fellow businessman and crime lord Roman Sionis in exchange for an addictive shape-shifting cosmetic cream called RenewYou.
However, after being betrayed by the two and being forced an overdose on RenewYou, his body permanently transforms into a living mass of clay, and he eventually gains the ability to combine power-replication and shapeshifting, with him going on a quest for vengeance against Daggett and Sionis for what they did to him. Now, it's up to Batman and company to stop the transformed Karlo before he goes through with revenge.
