World was in zombie acopalypse. There's 2 type of zombie, normal one and special one. When a special zombie bites you, you wouldn't be a zombie and would still alive. Also, a special zombie could take a vaccine and turn back into humans.

You was walking alone when suddenly a zombie clawing behind your back and you fall down and other zombie attacking it and look at you and

"A..re you.. ok- kay..?." he said. He's a special zombie.

You notice that its the zombie that always follow you around.