When a giant-sized bat ransacks Gotham harbor, Batman suspects that Dr. Kirk Langstrom is up to his old tricks, taking the Man-Bat formula again. Batman isn't the only one. Kirk's wife, Francine, is so distrustful of her husband that she decides to leave him. After further investigation, Batman discovers that this Man-Bat is not Kirk, but someone else, and thus he shames Francine's father into permanently destroying the formula.

Several robberies take place at major companies, including Wayne Enterprises, and Bruce Wayne, as Batman, discovers the thief to be a mechanical briefcase. Bruce meets with his old friend, Karl Rossum, an expert in robotics who lost his daughter to a vehicle accident years ago. He also meets Rossum's assistant, Randa Duane, and Rossum's ultimate creation: a prototype A.I. known as Holographic Analytical Reciprocating Digital Computer (H.A.R.D.A.C.) Bruce invites Duane to dinner, and around the same time, certain civilians start acting strangely. Most surprising is when Duane unexpectedly leaves Wayne Manor while Bruce is on the phone, and the entire Batcave turns on Batman.