|Complete Bright Lights, Flying City and The Cold Shoulder||17||ECHO Recorder dropped by Goliath (The Fridge)||2903 XP, $308, Rocket Launcher|
You need to have finished The Cold Shoulder before you can get this side mission, as the Goliath carrying the ECHO recorder doesn't appear until you finish it. He seems to appear more often towards the middle of the map and you need to kill him without the Goliath going berserk, so don't shoot him in the head at all.
You learn of a gun stash in The Fridge, who seems to be with the Goliath's brother, Smash Head. In order to get to him, you'll need to travel through the door where Laney came out of during The Cold Shoulder. This will put you in the Rat Maze area, which is filled with rat bandits. Once you reach another icy cavern, you'll see a large chest encased in ice. Clear the ice and open the chest to finish the mission.
You do not have to kill Smash Head, who spawns once you open the chest, for this mission. Note that there is an optional objective to kill ten midgets, which will likely be completed as you make your way to the loot stash. If not, then you'll need to hunt down midgets yourself, as while Smash Head will spawn Midget Boners, the mission is already over at this point.