DC Comics Presents: Batman - Dark Knight, Dark City #1

In these thrilling tales from BATMAN #452-454, The Riddler goes on a crimepsree - but when he has the chance to kill Batman, he let The Dark Knight live. What strange game is The Riddler playing? Plus, in a story from DETECTIVE COMICS #633, Bruce Wayne returns to Wayne Manor to find no trace of the Batcave, and Alfred without any knowledge of his master's crimefighting career. Has Bruce Wayne gone insane?