Late at night, a female student’s school uniform is discovered on a hill outside the city. Police arrive at the scene, suspect foul play, and begin searching for the missing person. The missing student is Cheon Ji-yun, a second-year at Cheongwang Middle School. She disappeared while investigating the case of a senior student, In Yu-jin, who had gone missing four years earlier. The detectives recall a now-famous statement made at the time by Yu-jin’s biological father: “My child was abducted by aliens.” And so the case begins to slowly spiral into the realm of the unimaginable.