This mission starts out with a cool cutscene. When you step out of the airlock you will hear someone whisper "Deliver us from evil". Go to the right of where you start to get a PDA on a bench outside the monorail. Use the health station and get the ammo from the open storage cabinet. Go in the monorail and start it with the panel. Then turn around and talk to the guy behind you. He will tell you about the invasion. It stops at Site 2 and gives you a new mission. Pick up the ammo in front of you and go through the northern door. In there a Commando Zombie will charge you. It has a VERY long reach with its arm so its best just to take the damage then shoot him real close in the head before he hits you again. Kill the solder zombie behind him. When you continue on you will find an imp and two zombies attacking. Kill them while strafing. Get the large med kit in the corner and go down the stairs close to the entrance and kill the two shotgun zombies. Pick up the PDA and it gives you access codes to the airlocks (953 and 826). Now back up the stairs you came from and kill the machinegun zombie. And be prepared for the two commando zombies that are behind you.

Go to the shelves and get some armour, clips, and rockets. At this point a zombie will shoot at you from the north and an imp will spawn. Three more imps will appear. Go to the northwest alcove and get the supplies inside. Once you do climb up the nearby stairs to a cured walkway. An imp will appear in front of you as well as to the side and another commando zombie will attack in front of you. Go east and down stairs to get armour and health and go back up to the top and continue. A commando zombie while bust through the door; once you kill him go through it. Use the health station and use the PDA to open the cabinet (the code is 142). Then type in the control panel 953. Then back track to the monorail until you get to six trites when they are dead get in the monorail and activate it.

When the monorail stops go up the ladder and kill the commando zombie running towards you (don't use a shotgun for this because he is far away). Go to where he came from to get a med kit and a clip and then go back through the door near the start. Kill the trite that comes out of the vent and continue. When you go around the corner one trite will attack from the front and one from the back. At the next corner five trites will near you. Run away from them and blast them with a machinegun. Go through the next door. Kill the commando zombie running away from you. If you follow him he will attack. Then find some cover because and imp, an zombie, and two commandos will spawn. Go down the nearby ladder to get some armour and then go back up. Go through the next door and jump through the broken pane of glass. Get the med kit and then activate the nearby panel. When you go through the door kill the commando on the other side.

When you go through kill the zombie on the balcony and the one to your right. Climb up the stair and go into the office to get a med kit and a PDA. It tell you the code for the nearby cabinet (364). It will also allow you to deactivate a turret later on. Go through the door near the office and kill the imp that spawns. Keep walking until you get to a door with a commando zombie behind it and blast it with your shotgun. Then kill the imp behind you. Keep going on until you see another commando zombie charge you through a pane of glass. Go into the room and be careful because the turret will kill anything that moves. Sprint across into the room the commando came from and deactivate the turret. Go through another door and use the code 364 on both cabinets. Now go through the airlock and proceed to Delta Labs 1.