In the grip of grief following the death of his young son, his marriage on the rocks and nearing bankruptcy, Parker reluctantly returns to work as a private investigator. Embarking on an unusual assignment to observe a woman from an abandoned apartment, Parker witnesses bizarre happenings surrounding her, unaware that the derelict building that he surveys her from has birthed a dark presence which slowly threatens to consume him.

Anja and five friends join anthropology student Dace on a journey to study a remote ancient rock painting. Their excitement vanishes when Mel becomes delirious after skinny-dipping in the waterhole. Feverish bleeding confused she physically and mentally regresses to a vicious predatory state. Mel has gone primal. Mels lover and friends realize they are the prey as she savagely hunts them down. Before they can escape another one of them starts to regress posing a hideous choice kill their friends or be killed by them. Their only hope of survival is through a cave where Anja learns too late the meaning of the ancient rock art they came to study.