How to use the line launcher - Batman Arkham City Episode 28

In this episode of Batman Arkham City I am on the hunt for Ra's Al Ghul. First I have to get around the restricted access area and then I encounter a bunch of armed goons who are blocking my access to the underground sewers. After I dispose of them one by one through stealth I head down into the sewers. The maze of tunnels leaves me bewildered and my only guide are sets of false chattering teeth. It seems we have both Penguin's and Joker's crews down here and they don't get on. Inevitably I encounter some more thugs and after taking them out I learn how to use the line launcher. This device saves me from attempting impossible jumps and you can even turn left and right by firing a line when you need to turn. I stop at a dead end and there seems to be no option but to drop attack a large gang of Joker's men. It's a tough battle but I end up victorious and I find myself in the subway system after hacking an entry console. It looks familiar and turns out to be the subway that we had already explored. After a brief look around I decide to call time and bid you farewell till my next video.