In this groundbreaking, painted graphic novel, the inmates of Arkham Asylum have taken over Gotham's detention center for the criminally insane on April Fool's Day, demanding Batman in exchange for their hostages.

Accepting their demented challenge, Batman is forced to live and endure the personal hells of the Joker, Scarecrow, Poison Ivy, Two-Face, and many other sworn enemies in order to save the innocents and retake the prison.

During his run through this absurd gauntlet, the Dark Knight's own sanity is placed in jeopardy.