As two new forces of evil--Two-Face, formerly known as District Attorney Harvey Dent until a courtroom accident left him disfigured by chance and fueled by vengeance, and the Riddler, who was previously Edward Nygma, an overlooked employee of Wayne Enterprises before his transformation into the most quizzical and dangerous of tricksters--join together to overtake the minds of Gotham's citizens and destroy Batman, their mutual enemy. In return for financing the mass production of his devious mind-controlling invention, the Riddler commits to helping Two-Face solve the biggest mystery of all--who is Batman?--not knowing that Two-Face's caped quarry and his own rival, billionaire philanthropist Bruce Wayne, are one and the same.