From Square Enix:
The Batman: Arkham Asylum demo opens as the dark knight and Commissioner Gordon return The Joker back into confinement at Arkham Asylum. But things soon fall apart as The Joker gains the upper hand and springs a trap, setting Arkham Asylum's occupants upon Batman. The demo offers gamers a taste of the fierce FreeFlow combat system, the cunning stealth of the Invisible Predator mechanic, and the feeling of becoming the WORLD'S GREATEST DETECTIVE as they navigate Arkham Asylum's imposing Intensive Treatment facility. Players can unlock character bios, as well as get a sneak peak at some of the infamous foes that Batman will encounter within the cavernous and macabre confines of Arkham Asylum. Featuring amazing graphics within an intense, immersive setting, Batman: Arkham Asylum exposes players to a unique, dark and atmospheric adventure that takes them to the depths of Arkham Asylum - Gotham City's psychiatric hospital for the criminally insane. Gamers will move in the shadows, instill fear amongst their enemies, and confront The Joker and Gotham City's most notorious villains, who have taken over the asylum.