You’ll need to make the long journey west to meet up with Javier and Charles in order to begin this mission. Beware that when you enter Blackwater, the area is on lockdown and you will be shot on sight by the Law. Once you begin the mission, follow Trelawny along the riverside as you follow the boat. Eventually the boat will come to a stop and you’ll need to ride down to the riverside with Javier and Trelawny. Equip your knife and remember to bring your Repeater with you for later in the mission. Silently follow Javier behind the two Bounty Hunters and dispatch the left one as soon as Trelawny begins his distraction.
The battle takes to the canyon ahead as you begin making your way up, be sure to stick to cover and aim for as many headshots as possible, you need 10 for the Gold Medal. The main concern in this shootout are the snipers above the canyon, make these your main priority and use Dead Eye where possible to score as many headshots as possible. As you begin making your way up the hill two more will assault you from the left, these are prime targets for more headshots.
You’ll eventually reach the camp where Sean is tied upside down to a tree. Carefully take aim at the rope he’s dangling from and shoot it to drop him to the ground. Once you take out the initial group of Bounty Hunters a final group will attack from the hills, use any Dead Eye you have remaining and headshot them. Head on over to Sean following the battle to cut him free and complete the mission.