Twenty years ago, a strange light filled the whole sky. Those who survived lived on without their memory of what happened before the Enigma. Those who died either remained dead, or woke up as the undead - armed with the memory the living had lost, but giving up their ability to walk in the sunlight. Unfortunately, they also woke up with a hunger for living blood.  

The living only made up 10% of the human population, and they went into hiding in the countrysides and at abandoned docks. The dead congregated in cities, carrying on their daily lives. 

For the living, this world is a deadly world.

Naeun ends up in the middle of a vampire city due to an experiment gone wrong. Right when it seems as if her life is about to end, she's saved by.... a bloodsucker who claims he knows her? 

To kill or be killed, that is the question.