"This is what the Watcher has been watching for. A danger older than the Earth threatens everything. And for once, the heroes who have saved the planet time and again find themselves almost completely powerless in the face of it. X-Men and Avengers will assemble. Spider-people and the Fantastic Four will come together. Heroes for Hire will fight alongside Champions. But none of it will be enough. The lights are about to go out. The world outside our window...is about to end."--Publisher.