In a world of emotionless Elites and heartless Monsters, Kim Iseul, a plain human tries to navigate in this world while keeping her identity as a human a secret. Being invisible was easy for her and everything was going well until one day when she accidently discovered an abandoned laboratory. A cursed laboratory which was supposed to produce successful Elites but instead it produced seven failed experiments. It was too late when Iseul had realized that she had walked into the monster's den... He was beyond normal...and she wants to save him. She believed that he still had humanity left... Iseul was a human--Heeseung was a monster. Together both broken souls navigate this cursed world by helping each other...but it wasn't as easy it sounds...