where yoongi, yn & woozi are childhood best friends, where both yoongi & woozi love yn, but yn also loves one of them. then when yn is in a relationship with one of them, she suddenly gets threat messages from a serial killer - but not an ordinary one. the killer is the world's most dangerous serial killer. not only has the killer murdered many people, but also raped one of the victims.
since then, the police have been searching for the serial killer. yn tells both yoongi & woozi that she feels watched and is getting threat messages. they both get more protective of her. one day, when yn is walking home alone and both yoongi and woozi are busy, she hears footsteps behind her - she knows it's the killer.
she runs home, calls and messages both of them, but neither answers. by the time yoongi and woozi check their phones, it's too late. they run to yn's house and find her body, covered in blood. she's been mutilated in a horrifying way. the killer left a note saying the next targets will be their families or close friends. both yoongi and woozi are overwhelmed with guilt and regret for not answering yn's calls. they inform the police and yn's parents, who arrive at the house in shock.
yoongi and woozi freeze - unable to explain what happened or how to break the news to her family.