In the Monastery Otherworld, start running forward through the corridor with the cells, towards the spotlight. Turn right, then run to the door at the end of the hallway. You see the girl running away. Keep chasing her. Open another gate, then notice a crack on the stone wall. Go through the crack and keep pursuing the little girl around the ravine and through another open gate. In the distance you see the Bogeyman striking a hammer, shattering some glass.
Go through another opening in the wall, and down into some flooded corridor. Go past the cell containing the brawler, then up some stairs and through a door. The girl is still escaping, stay on her track. The Bogeyman again strikes the ground with his hammer, creating a chasm. As you approach him, the floor crumbles beneath you and you fall down one level into some tunnels. The void is now giving chase to you.
Run through the corridors. Murphy will say that there must be a way out somewhere. And there is. Watch for the giant stone face carved on the wall on the right side of the corridor. When you see it, you are supposed to make a hard left. If you are still lost, refer to the image below which will show you where to turn.
Knock the cage behind you as you exit the corridor, then climb the stairs. Go through a door and into an outdoor area with a cemetery and some statues. Again, be sure to knock down cages as you pass them. Proceed to the door in the far end of the area, Then turn right and run through another hallway. You approach a very narrow corridor with some spike traps on the sides. You hear a voice: "You won't find yourself, Murph, until you face the truth."
Watch the pattern on the spikes. They strike two times, then stop for a few seconds. Take advantage of the the short pause to slip through. Do the same with the second spike trap. The harder the difficulty, the less time you will have to go through the Spikes before they emerge again.
The third and fourth sets of Spikes do not pose any threat (on easy and normal difficulty) so just pass through them. The fifth set of spikes strikes five times before stopping. Time your approach and shimmy through it as it stops.
After you clear all the spike traps, the void stops chasing you. Grab a first aid kit from the shelf on the wall. Enter a big chamber. The Bogeyman is there. It strikes the ground with his hammer, sending shockwaves at you. At the same time, some Screamers attack you. You have to fight the Screamers, while simultaneously avoiding the shock waves from the Bogeyman.
After the Bogeyman encounter, slip through an opening on the wall to your right. Find yet another first aid kit on the wall. Go through another long corridor and open the door, You hear some groaning. You appear to be in some sort of infinite corridor. Going down the stairs or through the door puts you in the same place where you started. The solution is to use the portraits to guide you. When you see the portrait with the small girl running towards the light, that is the door you need to exit through. See image below for help. In the "1 Stairs" area, go downstairs until you see the illuminated picture. If you missed it and get to the bottom, just go back up again looking for the correct portrait.
When you reach the second area with the stairs "2 stairs", go upstairs this time. Look for the same picture as a sign telling you which door to go through.