10 Comic Book Plots That Will Never Be Resolved
3. Batman's Involvement With The Flying Graysons
At the end of the event Final Crisis, Batman seemingly sacrificed himself to kill Darkseid. With Bruce Wayne gone, Dick Grayson took up the mantle of Batman to protect Gotham.
One of the first opponents Dick faces is Two-Face, who manages to break into the Batcave. Dick is able to defeat Harvey and even convince him that he's the same Batman as before. However, the location of the Batcave is now no longer a secret and so everything has to be dismantled and moved.
While taking apart the case that holds Jason Todd's Robin costume, Dick discovered that its base was hollow. Looking inside, he found a USB drive hidden by Batman. On the drive are numerous files on the murder of Dick's acrobat parents the Flying Graysons and the suggestion that Bruce knew something about their deaths that he was hiding from him.
Like a lot of entries on this list, the plot got lost during a change of writers. Judd Winick took a break from the title, intending to return, but ended up getting bogged down with other projects. New writer Tony Daniel left the mystery alone, probably assuming Winick would continue it at some point, but he ended up staying on the book until it was rebooted as part of the New 52.