In a rural village in Jeolla Province in 1983, Yeong-sik's older sister Mi-suk disappears without a trace that summer. Sang-cheol, Yeong-sik, and Byeong-su, who were chasing aliens, believe it was the aliens' doing and set out to find Mi-suk. In the process, Sang-cheol witnesses something. Decades later, Sang-cheol confronts the memories of that day again.