"In a tale from the early days of their partnership, the murder of an alien explorer bring the Man of Steel and the Dark Knight Detective to investigate on the moon. But there's more to this traveler than meets the eye, and the truth may have unthinkable consequences for Superman. Meanwhile, someone's been watching the investigation from the shadows-- none other than Lobo, come to collect a bounty that's been placed on Batman's head! Back in the here and now, the World's Finest must prepare Earth for the final days of Superman. With time slipping away, they'll need the help of their greatest allies in order to pull off one last-ditch attempt to save the Last Son of Krypton. And, finally, the rogues of Gotham and Metropolis team up to find an answer to the age-old question: who's tougher, Batman or Superman?" -- Page  of cover.