In this comic book, Arkham Asylum has been taken by Joker and other inmates. They have hostages and want Batman to go in, so he does that and enters to face not only his classic incarlelated antagonists but also his own fears and "internal enemies". At the same time, we'll learn the dark history behind the creation of the asylum itself.
A different comic, quite dark, even sad, with long line drawings sketching and shaping the characters but almost never sharp enough to distinguish details. I liked it.
If to complain about something, would be for the length, I had a 20th anniversary edition and half of it are scripts, sketches and notes from the creators, fooling myself into thinking that the comic was bigger and, while not short, is definetly shorter than I initially expected. Maybe was just the wish for more.