How did this Happen(Lumity)

This story takes place in a zombie apocalypse the whole world is in chaos but the only hope of getting out of is going back through the portal to the human realm. It may seem easy but it is far from that They don't know were the portal is so they have to survive until they find it. Luz is afraid of loosing another person in so is Amity but what they are most afraid of is loosing each other. Also it you don't like gore don't read this.