At the start of the level you will find either 2 or 3 "david" zombies. (the amount of zombies relies on how many players playing currently) Then you will go into the library where G told them (James and Gary) to meet him.
It doesn't look like G is there until you defeat 5 or 6 zombies and the players move further into the library. G is always found wounded, crouching behind a desk. As G is handing over his "file", (his guide to all the bosses) an axe zombie bursts through the door and attacks them.
After defeating the "axe zombie", (johnny) you go outside the library when you find you find yet another "johnny" zombie killing a civillian. (note that the civillian cannot be saved) You can also see a david zombie in the background, it can be killed using one bullet only. After killing the civillian, The Johnny zombie attacks you and after killing him, the civillian he kills makes one final quote stating that he doesn't want to die. Though he dies a second later...
This part makes you start having to save civillians from zombies. The first one is a woman being chased by a "Steve" zombie. (a david with a smaller head, a blue jacket, more health and the fact that he "karate chops" you) After killing the Steve, you will turn to the left to see a man being attacked by another Steve and two Davids. On saving him, he will show you the way out of the garden of the library, on letting him be killed by the zombies, They will turn around and attack you. The woman is seen crying behind James and Gary. James or Gary states that they couldn't help the man even though they clearly could, but chose not to.
In the next scene, a Steve and two Davids burst through the glass double - doors to the left of them. After killing the Davids and Steve, you go through the double doors and find a fountain full of frogs who (of course) attack you. (Note that the frogs take ONE HIT to die; just like the murrers later in the chapter)