Superman/Batman

After helping to run off Metallo from S.T.A.R. Labs in Metropolis, Superman learns that before becoming a cyborg, Metallo (as John Corben) was a criminal in Gotham at the time that Bruce's parents were murdered. He flies to Gotham, where he finds Batman investigating a crime scene in the middle of a cemetary. Metallo has been searching for his human remains. When they find him, Metallo shoots Superman with a shard of kryptonite. Superman falls into an open grave, and Batman jumps in after him trying to remove the kryptonite as Metallo buries them alive.