Sim-dan gets bullied everyday in his school, becomes a vampire after an unexpected accident. After accepting this change, he saves a blind person who fell down on a subway track, thanks to his power. His story goes on air on TV news all over the nation, and many people start to call him a ‘Hero’. On the other hand, Sim-dan’s friends start to wonder about his power and dark force, appearing after a long sleep. He is after the girl he loves and people around him.

A mysterious virus spreads out. Anyone infected feels the emotion of love, and the emotion amplifies until it kills the person in love. The pessimist Taek-seon, who likes nothing in life, is infected, and the researcher Gyun reaches her out to test her the medicine that he's developing. Soon Gyun finds out Taek-seon has special antibody, but Taek-seon slowly feels love to Gyun. Is this a real love or just a virus?

남편의 여자가 우리 집에 들어왔다 자신의 어린 제자 연미와 불륜에 빠진 남편 동혁 둘의 관계에 대해 모르는 척, 연미를 집으로 끌어들이는데…… 과연, 주희의 숨겨진 진심은 무엇인가? 나와 남편, 그의 여자와의 위험한 동거가 시작된다!