“Sis, we’re each other’s one and only ‘sisters,’ aren’t we?” Ryu So-Hui, a high school student who was often sick as a child but has since recovered and is now living a normal life, has a younger sister, Ryu A-Yeong, who is ill. A-Yeong looks up to her older sister So-Hui, but So-Hui begins to feel burdened by her sister’s devotion. Following a certain incident, the sisters’ relationship begins to sour, and they start to feel uncomfortable around each other. A cruel mystery thriller about two sisters, unfolding amid the family’s hidden secrets! (Source: Naver, translated)