The impossible has happened, and Batman is on the verge of being taken down by an enemy he cannot defeat: a virus for which there is no cure! And the only hope for his salvation is The Joker! Who infected Batman, what does the Clown Prince of Crime know, and how will the Dark Knight get that information? Together, the enemies crisscross Europe, desperate to find answers before time runs out. Collects the four-issue miniseries with a new cover by Jim Lee!