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.