"There is a witness. She is on the autism spectrum." 'Soon-ho' (JUNG Woo-sung) who once worked as a lawyer for a civil rights organization has set aside his beliefs and joined a large law firm. Working on a major case that could make him a partner, he wants to put 'Ji-woo' (KIM Hyang-gi), a teenager with autism and the only witness, on the stand to prove the innocence of a murder suspect. "Will you use me too??" 'Ji-woo' has difficulties communicating, living in a world of her own. 'Soon-ho' tracks her down to ask her about what she witnessed, but is unable to even make a proper introduction. However, 'Soon-ho' does not give up and he tries to get 'Ji-woo' to open up. In time, he begins to understand 'Ji-woo' but the two are destined to meet in court as witness and attorney. The truth was revealed when the hearts were opened