Son Chaeyoung has been the last six years locked in a psychiatric hospital, accused of murdering her father. The fantasy world that lives in her mind has been the cause of many medical studies, but no one doubts her being guilty. In a slip she manages to escape, returning a month after, by her own. A new corpse in her old house confirms everyone's suspicion. 

Regardless of this, her new psychiatrist thinks the opposite. Dr. Yoo little by little starts discovering that the fantasies inside Chaeyoung's head actually have a connection with reality. That the violent acts that covered her life, somehow, are connected with the misterious object she brought when she came back to he hospital: a necklace with a wooden pendant. Carved to look like a cactus, a Saguaro (Carnegiea gigantea).