|Complete Toil and Trouble||28||Mordecai (Sanctuary)||6983 XP, 4 Eridium|
Apparently, someone is broadcasting some horrible fake stories about you and Mordecai has tracked him to Arid Nexus - Boneyard. Once you arrive in that area, head to the waypoint and use the elevator to get to the platform. Open the door on either side via the switch next to it to reveal Hunter Hellquist, your target. Kill him, then return to Mordecai to finish the mission.
Note: Hunter Hellquist has the potential to drop The Bee when killed, which is considered one of the better shields in the game.