In this painted graphic novel, the inmates of Arkham Asylum freed themselves and have taken over Gotham's mental illness detention center on April Fool's Day and have only one request. That is for Batman to come into Arkham Asylum with them in exchange for their prisoners. Accepting their demented challenge, Batman is forced to live and endure the personal hells of the Joker, Scarecrow, Two Face and many other of his sworn enemies in order to save the innocents and retake the prison. During his run through this absurd gauntlet, the Dark Knight Detective's own sanity is in jeopardy. The mental patients of Arkham Asylum believe that Batman belongs in Arkham Asylum with them because a man who chooses to wear a Batman suit and hunt criminals all night cannot be completely sane. Parallel to this story runs the story of Doctor Amadeus Arkham, the man who created the asylum for the criminally insane and lost his mind to it.