Five Riddles for Robin

Batman has been kidnapped by the Riddler! The crook has left behind one of his infamous riddles, addressed to Robin. If Robin can solve the puzzle, he will locate the Caped Crusader, but that first riddle leads to another. Then the Riddler turns off all the lights in Gotham City. What, Robin wonders, is the point? When will the riddles end? If the Boy Wonder cannot find his partner by the next sunrise, Batman will be gone forever.