Batman Arkham Knight – Guide – Gameplay Walkthrough - How to Finish Off The Next of the Riddler's Challenges
by Shafi Choudhury
Once you get to the orphanage, go onto the rooftop and go to the lighthouse tower which it to the south-east. Look down and you’ll see enemies which are gathered by the entrance to the building. You have to take all of them out except for the Riddler’s informant. When you activate Detective Mode he’ll be the one that’s highlighted in green.