Masterson was a caravaneer who headed a Happy Trails caravan run into Zion Canyon, looking to delay Happy Trail's demise by trading with the Mormons in New Canaan, who had always been reliable for trade. This caravan run was important for the fate of Happy Trail's continued existance, so Masterson was understandably cautious when it came to anything that could slow the caravan down.
He had never been to Zion before and needed someone with a Pip-Boy 3000 in order to map out the area and its natural hazards. He used to have another prospector with a Pip-Boy on prior caravan runs, but he left without a reason shortly before the expecition into Zion; Jed presumed that something must have spooked him. To this end, he was looking for any wastelander with a Pip-Boy to replace that prospector; he offered 25 caps per day and a bonus upon reaching Zion and New Canaan. The Courier was able to fill this role, but was unable to protect Masterson and the other caravaneers from their untimely deaths when the caravan was ambushed by White Legs when they arrived in Zion.
Jed appears to have a close relationship with Stella. When she is shot, Jed reacts in a more dramatic sense than he does with the others. When the Courier threatens Ricky and makes him leave, Jed seems glad to hear the news.
Happy Trails Expedition: Jed and his team are looking for a person who can hold their own and help protect the caravan.
Arrival at Zion: Jed leads the expedition to Zion for the Happy Trails Caravan Company. Upon reaching the Zion Valley, he and the other caravaneers are killed by a group of White Legs who ambush the group. Nothing the player does can prevent his death.
With a Survival check of 50 the Courier can convince Masterson that the Courier can carry more raising the weight limit to 100. The weight limit increase may also be achieved through the Strong Back or Pack Rat perks.
"You know we ain't coming back this way for a good long while now, right? And you know about the weight limit? I don't want no whining about "Oh, Mr. Masterson, I left my one-of-a-kind plasma cannon back at base, can we go back for it?" You sure you're ready now?"
↑The Courier: "Do you know anything about their religion?" Jed Masterson: "I ain't a prayin' man myself. They paid for their goods and dealt square with us, that's all I ever cared about. But don't think that just because they're religious that they're pacifists. They take care of their own, and they're damn fine marksmen too." (Jed Masterson's dialogue)
↑The Courier: "You don't know what happened to their mission?" Jed Masterson: "Nope - hence this caravan. If we don't make contact with the New Canaanites, Happy Trails might as well just shrivel up and die." (Jed Masterson's dialogue)
↑The Courier: "Hey, man, I'm cool. I got a big backpack and everything!" Jed Masterson: "[FAILED] That's exactly what I'm worried about. We got us some passes tighter than a virgin on her wedding night up there. Last thing I need is some greenhorn getting stuck on a rock, slowing the whole caravan down." (Jed Masterson's dialogue)
↑The Courier: "Hey, man, I'm cool. I got a big backpack and everything!" Jed Masterson: "[FAILED] That's exactly what I'm worried about. We got us some passes tighter than a- well, tighter than a Chairman's fist up there. You get stuck in there, you'll slow the whole caravan down while we pry you loose. Begging your pardon, ma'am." (Jed Masterson's dialogue)
↑The Courier: "I understand this caravan is headed to Zion. What can you tell me about the area?" Jed Masterson: "Well, I ain't never been inside, myself. Did some trading with the New Canaanites from their mission there, but that was all on the outskirts. All the old ways in and out were destroyed after the War, but we got ourselves the location of a pass the New Canaanites use - that's our way in. That's why I wanted someone with a Pip-Boy on the caravan - the map'll be helpful for checking the topography, keeping us on the trail." (Jed Masterson's dialogue)
↑ 6.06.1Jed Masterson: "Damn good thing you came along, too. We had another prospect with a Pip-Boy, but he done skedaddled. Something must've spooked the boy." (Jed Masterson's dialogue)
↑The Courier: "Tell me more about the job." Jed Masterson: "The job is simple - help us get this caravan into Zion and find New Canaan. The pay is 25 caps per day, half up front, half on return. You'll get a bonus if we make it into Zion, plus another bonus if we reach New Canaan. Oh, one more thing - don't mention the name Joshua Graham to anyone. Anyone." (Jed Masterson's dialogue)
↑Jed Masterson: "Shhhhh! Hold on, now...Could swear I heard something up ahead.Goddammit, ambush! Cover, people! Watch yourselves!" Ricky: "You want some, assholes? You just pissed off the wrong guy! And that means Ricky!" Stella: "Shut the hell up, Ricky! Might as well be waving at them!" Jed Masterson: "Holy hell! Stay low, people, stay low..." Stella: "Enough of this! We're sitting ducks here!Here I come! I was a sheriff once, goddamn it!" Jed Masterson: "Stella!... Oh no!Don't you die on me, woman, you hear?" (Jed Masterson's, Stella's, and Ricky's dialogue)
↑The Courier: "Relax, I've humped this load across the Mojave on my own two feet long enough. I can handle it." Jed Masterson: "[SUCCEEDED] Hmm... all right, I reckon you know your limits. You keel over on me out there, though, and I'll leave your ass. After we take everything useful you crammed in your pack." (Jed Masterson's dialogue)
↑The Courier: "Not only could I carry my own gear, I could carry yours, his, and one of your brahmins'." Jed Masterson: "Heh. I do believe you could." (Jed Masterson's dialogue)
↑The Courier: "Don't worry about me. I'm used to finding out-of-the-way places to stuff my gear." Jed Masterson: "Heh. All right, I'll believe you - Lord knows I ain't going to pat you down to find out for myself." (Jed Masterson's dialogue)