Head to Goodsprings source and towards the water trough, and the Courier will see Barton Thorn wandering around aimlessly. Talk to him, and he will plead for the player character's help to save his girlfriend trapped by geckos. He will give the Courier clear directions on where to go: head towards the broken radio tower, then turn right. There, one should be going up an incline.
As the Courier goes further up, they should see a path forking off towards the right. There is a refrigerator, bed, footlocker and some loot. Be careful, however, of the three bear traps. This area is also a Wild Wasteland trigger area.
Once at the top of the incline, one will discover that there is no one to be found, and as the Courier is heading down the hill, Thorn will run up and tell them he is "sorry," but he needed someone to clear out the geckos so he could get to the stash. At this point, Thorn will become hostile and attempt to kill the player character. Killing him ends the quest.
With the Animal Friend perk, killing the geckos is not necessary, as they will not be hostile towards the Courier. Thorn will none-the-less say, "Thanks for clearing out the geckos for me" as if they had done so. The geckos could potentially kill Thorn immediately after he says this.
The player character can ask for 50 caps as payment for helping him. Barton will agree to this, however, he is lying and will never pay up.
The prospector's camp can be reached without exiting the invisible boundary that finalizes character's attributes and skills by maneuvering southward along the clifftops from Victor's shack. This route is useful in reaching the camp while avoiding the geckos guarding the ridge as well.
After killing Barton Thorn, his corpse will disappear from the game after leaving the cell for a while.
Because of the geckos spawning in the area, he can sometimes be found already dead before one can meet him.
Behind the scenes
The title is a reference to the Coen Brothers' movie Barton Fink.
Sometimes, Barton Thorn will not come up the slope behind the Courier, but after waiting or sleeping, he completes the quest. [verified]
During some instances, Barton will appear to be facially randomized, along with his clothing. [verified]