On this page of the game guide to Borderlands 2 you will find a detailed description of the side mission titled This Just In. You can start this quest in the Sanctuary location after completing the main mission named Toil and Trouble.
Arid Nexus Boneyard
2) Radio station
Accept the mission from Mordecai  in Sanctuary and use Fast Travel to move to Arid Nexus Boneyard. Approach the  radio station and use the elevator from the screenshot to get higher (Use the lever).
Above, open the door on the right or left side on the small building. Inside you will find Hunter Hellquist which you have to kill. During the fight Hunter will also receive support in the form of a couple Robots. After eliminating the Hunter, return to Mordecai  to end the mission and collect your prize.