The devil you know

Yujeong is a popular instructor who believes in human goodness. She meets Sunhee, a charismatic businessman who expresses interest in her. While trying to protect her family, Yujeong attempts to keep distance from him, but an unexpected event that very night changes everything. Sunhee’s behavior becomes completely different, and in that moment of drastic change, Yujeong finds herself drawn into a dangerous trap. Meanwhile, Yujeong’s close friend and brother figure Gangsu, who distrusts people, senses something is wrong. As the dark side of Sunhee’s personality reveals itself, the relationships between the three become increasingly tense—and only the truth, twisted and buried, can resolve the chao.