Batman & The Joker: The Deadly Duo #3

Synopsis

Trapped by an unknown enemy, Batman finds a way out, but fails to save the lives of the parents of a young boy. Returning to the Batcave, he finds that the monster tooth with Joker DNA has mutated and is absorbing other organic material. Batman's analysis of the genetic material leads him to a company run by an acquaintance, but needing more evidence and needing to locate the kidnaped James Gordon, Batman turns to the Joker for help.