PHKim Mo-Mi (Lee Han-Byeol) is an ordinary officer worker. When she was a child, she dreamed of performing on a stage, under bright lights. As she has aged, she's gotten "ugly," but she is proud of her good-looking body. After her workday, and when she is at home, she puts on a mask and streams a live broadcast of herself as Mask Girl. She gets involved in an unexpected case.
Joo Oh-Nam (Ahn Jae-Hong) is Kim Mo-Mi’s colleague at work. He has a complex about having an ugly appearance. He is a fan of Mask Girl and learns Ko Mo-Mi is actually her. He has a crush on her and becomes involved in an unexpected case with Kim Mo-Mi.
Meanwhile, Kim Kyung-Ja (Yum Hye-Ran) is the mother of Joo Oh-Nam. After she divorced, Kim Kyung-Ja raised her son alone. He is the most precious thing in her life. One day, her son goes missing. Kim Kyung-Ja begins to search for his whereabouts.