You'll find yourself perched on a wire. Glide over to the ledge on the side and follow the hallway around. You'll come to a low gap by a trickling water pipe. You want to run towards this and hit the crouch button. You'll slide through the hole to the other side. Now make your way over the pipes here and you'll eventually come to a railing that appears to be on fire. If you approach, Batman will say something about how you'll be boiled alive. Enter detective mode and look dead ahead. There will be hatch across the gap. If you push up on the directional pad, you'll select your Batclaw. Aim and shoot at the hatch, then repeatedly tap the A button to open it.
Go over to the rail and drop down. Head towards the center and drop over the ledge. Slide to the left and then climb up again. Turn left and go onward. You'll come back to the center section again but you'll be able to hop on the rail in front of you. Do so and walk over the middle. When you run out of rail, turn right and hop to the next one. Use this to cross to the other side. Follow this platform around and at the end, activate detective mode. You'll notice that the floor is a blue color and has a "Pow!" symbol in the middle. Select your explosive gel (left on the directional pad) and then aim and shoot it on the blue surface. Back off from it and follow the command prompts to detonate it. Drop through the hole.
Head forward and crouch under the pipes. Don't walk into the pipes spewing steam/water. Instead, choose your baterang and use it to hit the button above and to the right of the hole in the wall. You'll automatically crouch. Just follow this crawl space until you can see into a room with inmates. From here, take a right and continue to follow the path until you come to some pipes spewing fire. After a second or two, the flames will die down so you can cross. Be quick though because the flame will return to its normal size quickly. Just past the flames take a left.