Three friends; Charlotte, Adrian and Viktor, have decided on being the first people to get through an unexplored cave system inside a deserted mountain alive. Filled with a sense of adventure they commence a challenging descent, unaware of the nightmare that awaits them. A couple of years earlier, two foreign divers drowned while exploring a part of the same cave. One of the divers was never found, and in the time that followed the cave was closed off. The three friends defy the restrictions, and with no backup, they begin their journey, but what meets them in the narrow, damp darkness is their worst nightmare.
Libby is plagued by disturbances since moving into a new home. She blames it all on her stepmother, Karina, who tore a photo of her birth mother. Libby dislikes Karina, and once even attempted suicide because of her stepmother. Despite all this, Karina continues to love and care for Libby like her own child. When the entity in the house tries to kill Karina, she tells her husband Sam about it, but Sam doesn't believe her.