When a potholing expedition goes wrong, a group of
women find themselves trapped in unchartered caves with no means of escape and an inadequacy of survival gear. Their psychological and personal welfare is put to further test when they
discover they are not alone and are being hunted by blind, vampire-like predators.
Unlike many modern horror films this maintains tension
throughout, locking in the claustrophobia early on before pouring on the scares in abundance.
The acting isn't spectacular, but it is made up for
with the atmospheric cinematography and production design.