Let's recap for a little... Three survivors have wakened up in their apartment from a building in Groningen. These three have a plan to escape this building, and that it is by taking their chances to crawl into air vents who were leading them to the armoury room, a room made to store guns, riot shields and ammo. Since the military wasn't going to rescue them, they instead gave them enough fire weapons, and some melee weapons to protect themselves against those nasty mutants.
These three have successfully finished their first day of the mission, and when they landed in the armoury room, they observed that someone from the building is there, but his body. Apparently, he committed suicide by shooting a shotgun shell into his mouth and destroying his head. Mike got sick when he saw that head splashing on the ground, but Ronald and Gerald didn't get sick, they instead feel awful cause he decided to die this way. While they were taking the important guns, Mike sees the body has the keys to this door. He takes the keys, but before he is about to use them, he asks his "friends".
"Should be a good idea to open the door and go to the halls?"
"No, idiot." says Ronald who is taking the keys from Mike. "The best idea would be to go back into the air vents, and remain there until the military would come."
"What if they didn't come?" asks Gerald, and Ronald is turning around, angry, he was about to push the old man, but he aims his gun at that corpse who was starting to move a hand and he shoots his first bullet from the Pistol int zombie chest, who stopped him from moving even an inch.
"They can move even without a head?!" scream Mike.
"Shh." warns Gerald. "We do not want to attract the ones in the hallway. Anyway, how many do you think are there?"
"Probably an entire ocean, but what do you want to do, old man? We cannot do anything, except praying to be saved by the military."
"... There is another way." says Gerald to those two survivors. "We could try and barricade this door back, but, to do that, we have to first find a way to the ground floor."
"We could take the air vents." says Mike.
"Or we can try the fire stairs. The ones people are using when a fire erupts in a building. I think this one works even for zombies." jokes Mike, but nobody is laughing, which is making him feel quite awkward for him, and shame that he jokes in these hard times.
All three of them later agrees to do a compromise. Mike is taking the other type of stairs, while Gerald and Ronald are taking the air vents. Mike has not encountered some dangerous zombies while he was taking the stairs, but when he was close to going downstairs, he encountered a few reanimated corpses who are having their back turned and blocking the way to the ground floor. But Mike, being on one floor, breaks the window of an apartment. When he breaks the window, he sees one zombie child who is walking faster to the window. He was close to grabbing Mike, but he uses his pistol and he shots the zombie child head, who falls on the floor of the house.
He wanted to enter that house, but his gut is saying to not even try to do this shit since this might be a shit movie. He also remembers that rule from zombie movies: "Double-tap.". He goes to the other window of the same apartment, and this one leads to a kitchen. He enters the house by taking the window and he is heading into the room where the child got to shoot and zombied earlier. Mike shoots that kid again, and he falls on his knees. Feeling guilty that he killed an innocent child who didn't know what to do. He stays there for a few more minutes, and then he breaks the door, and he uses his shotgun and pistol to kill the zombies on the first floor, while the other two survivors are taking the air vents to the ground floors.
Ronald and Gerald are landing into the kitchen from a ground apartment, most likely the one from the room where the landlord was living, until they found him later on into the bathroom, having his legs cut and put into a bathtub. He was trying so hard to get out of that bathtub, but he didn't make it at all, and he will never will because Gerlad has quickly stabbed the poor guy head with a screwdriver he found in the air vents. After they finished the landlord, they get it to the business.
Their strategy is simple. One of them, most likely Ronald, will open the door for a short time, hide behind the door, and opens back, while they are going to kill the zombies who entered the room. they did that a few times, and this worked, but after the third time they did that, Gerald and Ronald agree to take a small break.
"I wonder how is that store clerk doing." says Ronald to Gerald.
"He knows what he is doing." says Gerald reloading his UZIs he has taken from that armoury room. "Whatever he was doing in his previous life, he probably knows how to handle a gun as small as a pistol."