Rewards:
Head to Kupka Ranch and talk to the interesting character named Zip. Ride with him to reach the Flatiron Stockyards where the cultists are drugging up various animals.
Upon reaching the location, you’ll have to kill all the drugged animals as well as the peggy handlers. Attack using whatever tactic you want and deal with the targets. You can have Nick drop bombs while you designate the targets from cover. This will make it easier for you to sweep the remaining enemies and animals.
Once the hostiles are eliminated, you’ll have to provide cover to Zip as he plants an explosive. After that, take cover and take out any cultist reinforcements sent your way. Kill every last peggy in the area to complete the mission.