Cops Behind Bars is a side mission accessible once the level 13 Lunatic Fringe is started. This missions is started by talking to Sergeant Reeves at the door after the hallway, along with Detective Preston who starts What's In The Box?. Finishing it is required in order to get the Oh, I Get It feat which is worth 25 Points. It take place in the Joker's Funhouse. The objective of the mission is to save the caged police officers inside the Funhouse on your way to Harley Quinn to save Robin which is your main quest.