After you invade Raxus Prime then you have to go to Cloud City. Rahm Kota says there is a senator called Garm Bel Iblis who is against the Galatic Empire. You come on to the planet and see a fight between Cloud City Guards and criminals. The guards win and you find Lobot with them. He informs you that the senator is going to negotiate with Chop'aa. You fight your way through criminals you are ambushed by a gang of Mandalorians. Use the metal crates on them, when you throw it at them it explodes in electricity. After you defeat them and more criminals you meet Lobot again. He says a mercenary named Kleef kidnapped the senator.
After you make your way through you meet Kleef repairing two battle droids. He said he gave Garm to Chop'aa. You get prepared to fight him. After you defeat the droids, you throw him out a window and he gets hit by a flying car.
You fight your way through to Chop'aa and yell " stop! " He says "your talks have failed, this is how I negotiate!" First you must battle some mandalorians. Then his Basilisk War Droid. After it explodes in flames, you fight Chop'aa. When you finish, Lobot and his guards come to help Garm. He says he'll join you're rebellion and that he will contact Kota soon.