Eight school friends travel to a vacation house in the middle of a forest to bid farewell to Jin, one of their group who is going to study abroad. The trip allows them all to go back and reminisce over the memories of their high school days. However, a series of disturbing events cause tension and unrest in the gang, who begin to suspect there is a ninth person hiding somewhere in the house. When things take on a sinister turn, and they try to unravel the mystery, dark secrets from the past come back to haunt everyone. They realize that if they want to survive, they must quickly find out who is behind the deadly and bloody occurrences.