How to unlock: the quest becomes available after you start the Underground Undercover quest, talk to PAM in Railroad HQ (M6,2).
Once you progress in the main story and you receive the Underground Undercover quest, you will be informed about this quest by the Drummer Boy. In order to continue it, keep returning to the robot from time to time. The quest is repeatable and during it you must go to selected location in order to get rid of the Coursers that can be found there. The Coursers are exceptionally resistant to gunfire damage and less resistant to energy weapon fire. They are completely immune to poison and radiation and their limbs aren't so vulnerable to being torn out. Each time after defeating them you will be informed that you can return to the base and report to PAM. The number of the locations is limited and after some time they will start repeating.
Quest rewards: from 100 to 300 bottlecaps, sometimes a random armor part