In this level, zombies have gotten stronger, so shoot them faster. At the beginning of the level, you will see a vent. Shoot it quickly and you will end up in a dinning room. If you didn't shoot the vent, don't worry, after that you will find a bridge. At the end of the bridge is an arrow. Shoot it and the bridge will come down and you will pass though the dinning room. If you blast down the book shelves, you will find a person with a health.
Boss: Hanged Man
His weak point is his chest and stomach. For the first part, shoot the bats. Then shoot his weak point. To kill him faster, aim closer to the screen. Never look away from him! When he flies at you, try to draw a bead on him before he can attack you.