Bane (2008)

An experiment in human suffering.

Held captive in an underground prison by a sadistic sicko who fancies himself a surgeon, 4 women fight for their lives, knowing the exact time they're scheduled to die thanks to a crudely carved set of numbers on each of their bodies. None of them can remember how they got there, but if any of them figure out the secret to their imprisonment, they stand at least some chance of surviving.