Five members of the mountain bike club, Sangaja. To ride a mountain bike, we head to Chiaksan Mountain, where Min-joon's Uncle villa is located. After arriving at Chiaksan Mountain and enjoying the ride, strange things began to happen to the party…. And something unidentified chasing them! A desperate survival game for Sangaja's party to survive on Chiaksan Mountain begins.
Ji-Na works as a contract employee at a hotel. She appears to live a normal life, but, internally, she is filled with an inferiority complex. One day, she hears that her older sister Ji-Hyun is missing. Ji-Na goes to Rose Mansion Apartment, where her parents live. There, she faces unexpected cases. She can't trust the residents at Rose Mansion, who seem suspicious. Ji-Na seeks out the truth in her sister's disappearance with the help of Detective Min-Soo . Min-Soo is the only one who believes Ji-Na.