I Need OCs

DO NOT STEAL MY STORY OR IDEAS (Does not connect to any of my other books!) (Y/N) has been living this life for 2 years. Has not seen her old friend in those years. She is with 3 new friends and her brother. 2 years ago zombies some how go out of the under world and made it the upper world. They took the human land and killed 2/3 of the humans. The humans that are left are fighting for there life. What happens when see finds her old friend from high school? What happens when her old friend has new friends?