In this chapter, Batman needs to disable three communications disruptors in order to hack his way into the Iceberg Lounge.
Getting to the Museum
Rather frustratingly, even if you know where to go, neither the disruptors nor the guards securing them will appear until you've attempted to hack into the Museum first, so head over there, following the objective marker. When you enter the Museum, you'll encounter knife-wielding guards for the first time. Simply hold Y/Triangle and tilt the analog stick away to dodge them. After both of the knife freaks are down, smash through the window to the right of the entrance and try to hack the terminal with your Cryptographic Sequencer. It won't work, and Penguin gets in a good laugh. Batman will then program in the potential coordinates of the disruptors. Exit the museum.
Finding the Disruptors
Initially there are two disruptors: one just north of the Bowery, and one on top of the Museum itself (both of which are pointed out in the accompanying video). To save yourself a lot of tedious backtracking, head to the Bowery disruptor first. There are four guards stationed near it, all of them armed. Your best approach is stealth.
Just like in the video, take out the farthest inmate when he turns around. His friends will go and investigate, so take out the guard in the bottom-right corner now. The path they take from one guard to the next will eventually force them to split up, and you can take out the two remaining guards silently. Once they're down, you'll need to destroy all three panels on the disruptor to shut it down.
Now head back to the disruptor that's right next to the Museum roof. This one's a straight-up brawl, so beat them all up. Once you've shut down the second disruptor, head towards the subway (its location is also pointed out in the video). There are two guards stationed there, but every guard outside will ignore you once you've entered the subway, so either take them out or run past them and down into the subway.
The Subway Tunnels
After taking the stairs down, turn right and go down more stairs. Go past the vent and turn left. After a brief sliding and jumping obstacle course, punch through a weak wall and there should be three guards staring at a poster of Solomon Grundy. Beat them up, then head left towards the electric shutter. Overload it with the Remote Electrical Charge and slide underneath to the Subway Terminal.
This map is probably the toughest Predator section yet, but if you can take out the straggling guards in order to make the group surrounding the disruptor split up, you should be fine. The video shows one of the faster ways of doing this. After it is destroyed, backtrack towards the Museum to start the dungeon properly.