Debt Collector

 is a quest in Fallout: New Vegas.

Quick walkthrough
Talk to Francine at the Atomic Wrangler, and ask if she needs any work done. She will inform you there are three individuals that owe the casino caps. In total it will be 600 caps owed, and you will gain 150 caps if you return the caps to Francine. The three individuals are Grecks, Santiago, and Lady Jane.

Grecks: Fairly straight-forward, if you tell him you are with the casino and will be harmed if the caps are not returned, he will hand over the caps.

Santiago: Santiago will deny that he owes caps, but a punch to the face (in dialogue), and he will quickly hand over the caps.

Lady Jane: The hardest to obtain caps from. She does not deny that she owes caps, but her caravan was lost in Broc Flower Cave. You can travel to the rat infested cave and retrieve the caps from the caravan, but if you have the Lady Killer perk you will have a unique dialogue option and she will hand over the caps immediately. Note that the caps from the caravan in Broc Flower Cave will still be there for the player's taking after you get the caps directly from Lady Jane.

Killing Caleb McCaffery: You will need access to The Strip, which will require 2000 caps, or a passport. When you find Caleb, you will either have to kill him or have a speech of 40 and convince him to give you his hat. He can be a tough opponent, with his caravan shotgun. When you kill him he will have 20 gauge ammo and slugs on hims, as well as his gun, his hat, and duster. When Francine is informed she will award you with another 150 caps, and McCaffery's room. (which can be used as a player house)