He who suffers when all lights are off. She who seeks vengeance. Them who loved and pained. Being drowned in her sinful events and inhumanity, Cloud Heather struggled hard to fill herself with the need of taking her revenge with the very man who ruined her entire life. She has the perfect plans, she got the perfect notebook, she has her ace. All that she could only ask for is time and chance. With his powerful domination, angst and brute, Savier Choi aims to stand present with all his psychopathic retarded ex-girlfriend would plan to do. He signed a contract worth his entire riches just to perfectly get back to the very lady who left him hanging six years ago. When you define criminal, you mean HER. When you define pervert, you mean HIM. And when you define love, you mean... BLOOD. When their heart pleads for revenge, how sinful does it have to be?