Female Prisoner Sigma(2006)

Female Prisoner Sigma is a horror film set inside a brutal penitentiary where young women are stripped of their identities and humanity. An inmate known only as Sigma discovers that the prison harbors something far more sinister than its corrupt guards and sadistic wardens—an ancient evil that hunts the terrified inmates within its concrete walls. As this invisible horror feeds on the tortured souls trapped inside, Sigma must confront a nightmare beyond imagination. But Sigma arrived at the prison with her own hidden agenda, and she may be the only one capable of facing the darkness lurking in the shadows. Survival means confronting a terror worse than death itself.