Detective Comics #697 1996

In Detective Comics #697, Batman investigates a series of villain disappearances, including Two-Face and Charaxes. His search uncovers Lock-Up, a former cop who has established a private, maximum-security prison for Gotham's criminals. This issue is notable to collectors as it marks the first comic book appearance of Lock-Up, a character originally introduced in Batman: The Animated Series. The story also features Commissioner Gordon's return to his role, setting the stage for a three-part storyline.