"I want to be you" is a sharp psychological thriller fueled by jealousy. The story connects Min-hee, a class president whose identity is being stolen by a social outcast, and Ah-reum, who returns home after 16 years to care for her reclusive brother. Their lives violently collide during a brutal "Mother-Daughter Murder Case," where a lone witness confesses a chilling, bizarre scene to a detective, reconstructing the tragic events of that fateful day.