Soon-kyu, a high school student, caught sight of a UFO by chance with his classmates. To find the UFO, they leave for a so-called ‘UFO mountain’. When they arrive there, they meet a girl named Ji-hyun who tells them to leave. But they don’t turn back and keep their steps towards the mountain. 3 days later, they come back and insist they’ve contacted aliens the last night except Soon-kyu who blacked out due to overdrinking. After hearing that Ji-hyun’s missing, he leaves for the mountain again to answer his own questions- UFOs, aliens and Ji-hyun.