Second Sister: High school student 'Ji-eun' was the victim of the crime, but distorted online posts and malicious comments made her into the perpetrator in the public eye, driving her to take her own life. Her sister 'So-eun' finds detective 'Jun-kyung' to uncover the truth behind her sister's unfair death, and he begins hunting down a suspect in cyberspace. As clues are revealed one by one, the case grows from a simple rumor into a complex web of truth involving anonymous accounts.