These keys are given at the end of each Riddler’s objective/task. In order to save her, you have to get 9 keys. NOTE: We finished the challenges in our first playthrough – there might be differences in New Game+.

The last Riddler’s Revenge objective requires you to find all the Riddler Trophies around Gotham in order to fight their creator, Edward Nigma aka The Riddler. Because you need the Batmobile to enter these objective areas, you have to progress through the main story.