Nam befriends the bullied boy Thongsook as kids and she asked him about the necklace he wears around his neck and he told her to protect him from evil spirits, he takes off and gets possessed and she freaks out.
Now college students Nam and Thongsook are still friends but her boyfriend doesn't like him and her friends think he's weird, they go a private island unaware of it's sinister. Then Thongsook shows up unexpected and Mam's boyfriend and his friends decide to teach Thongsook a lesson about intruding where he's not invited so they take his necklace [unaware why he wears it] off and locks him in an abandoned building. So when Nam finds out she gets upset and tells them to go look for him but it's too late and all hell breaks loose.