Primal (2010)

A camping trip in the remote Australian wilderness becomes a nightmare for six friends when one of the girls, Mel, becomes infected at a nearby water hole and descends into a primal, predatory state. With fire as their only defense, they struggle for survival, unaware that Mel's not only hunting them for food, but is also serving the needs of an unknown ancient entity within the mountain. As the night progresses, tensions within the group escalate and their best laid plans have increasingly disastrous results. Finally the last two survivors realize that their only chance of escape is to go through the mountain, unaware they're entering the belly of the beast.