Crisis on infinite earths

"As their worlds are erased from existence one by one, can the heroes from different Earths band together to stop the destruction of all existence? It's going to take the combined powers of two Supermans, the Flash, a new Superboy, Supergirl, Alexander Luthor, and countless others to fight the madness, and not all will survive. The entire 12-issue Crisis on Infinite Earths saga is collected here in a pocketable, DC Compact Comics Edition"-- Provided by publisher.