Park Soyeon is the Beauty Killer.She wears a mask so nobody except for some cops who knows how she looks but it is widely known that she is very beautiful. Her brother, Chanyeol needs surgery, forces Soyeon to agree to the order which is murdering Cho Kyuhyun. His death comes with a pay for Chan Yeol's surgery but Kyuhyun hears that the Beauty Killer is after him and has people after her. She is attacked and shot but a passerby, Oh Sehun who finds and helps her. The problem is Sehun is a senior detective and knows who she is, but still helps her. Soyeon stays with Sehun for awhile and soon has feelings for him. Soyeon is forced to find money for her brother, possibly kill Kyuhyun and a way to confess to her crush.