In a remote mountain range, six
girlfriends meet for their yearly adventure, a caving
trip into the arteries of the earth. The group makes
their way through the remote cave system, enjoying
the hazardous but beautiful surroundings. Then,
deep inside the cave, disaster strikes when their
route back to the surface is blocked by a rock fall.
When they learn that Juno, always pushing herself
that little bit further, has brought them to an
unexplored cave, and that no one is coming to rescue
them, the group starts to splinter.
Left with no other option, they push on through
the cave, praying for another exit. The women battle
through this harsh underground world, pitting their
strength and determination against each new challenge.
Unbeknownst to them, there is something else lurking
under the earth, a race of monstrous creatures hidden
from the light, evolved to live perfectly in the
dark. As the friends realize they have become prey,
they are forced to unleash their most primal instincts
to face the creatures. As old wounds break open
and loyalties disintegrate, the women realize the
horrible truth they have most to fear from one another.