The Descent

Neil Marshall's 2005 claustrophobia nightmare works on two levels simultaneously. On the surface, six women are trapped in an uncharted cave system with blind, predatory crawlers. Underneath, it's a devastating story about grief, betrayal, and psychological collapse. The night-vision sequence is the single most anxiety-inducing scene in modern horror. The UK ending — darker and more hopeless than the American cut — is the one that hardened fans insist on.