Action Comics #539

Direct

The Atom uses the Time Pool to try to help Superman get to the past to stop Lord Satanis and Syrene. Flash does the same with the Cosmic Treadmill, but both efforts fail. Back in the past, the other Superman is still a pawn in the war between Satanis and Syrene. Clark Kent shows up at the Daily Planet, and promptly keels over. Clark Kent is dead! Meanwhile, Satanis manages to take over the body of the Superman in the past. And Clark Kent's autopsy begins.