Instructions
Play through the game until you're given a choice of two routes to get to the next area. Choose the left route for the Bella Sisters. Hide Ashley in one of the red containers while you clear the area of infected villagers.
Jump down into the center area to initiate the fight with the Bella Sisters and several infected villagers. Climb back up the ladder, then knock it down so that no one can follow you up. Equip your shotgun if you haven't already, as it has a large range of fire and can deal with several enemies at once.
Put your back to a wall or take another position where nobody can surprise you from behind. Shoot the enemies as they come at you, and if your back is covered you'll be able to kill them all from a distance at no danger to yourself. Keep killing enemies until the spooky music changes back to normal.
Loot the bodies of the Bella Sisters for a camp key and a ruby. Whistle to get Ashley out of the red container and back by your side. Jump back down into the center area and use the camp key on the door.
Break through the boarded window in this area and jump through it. Smash the barrels in this new area to uncover the Red Gem, which is the only other notable treasure along this route.