Before the mission, select a bought sawn-off shotgun, and a revolver. You will have to kill most of the enemies in the level with the revolver, so it may take some time. Use the "cover" (X) ability often. After you approach her "cabin" on the left is a big rock, go behind it and stand, Do not use "cover", but face the opening where she runs at you with the shotgun. When she comes around the corner, get two good shots off then run up to her and use the melee attack (B). When she runs away, reload. You may have to use Deadeye a few times, but it should work. Note: Along the edge of the cliff is a ledge below. It contains a chest hidden in a cave that has health. There is also another one slightly earlier in the level, in a similar location.