Detective Todd Richards is assigned to investigate the mysterious death of Father O'Malley, a priest who committed suicide in an abandoned convent. A routine investigation takes a turn for the strange, however, as Richards finds out that the convent is rumored to be "demon possessed" and a mysterious nun appears whenever the detective comes into the decrepit old building. Richards is a skeptic of the supernatural and denies all of the strange goings on in the convent but he soon realizes that the devil is not mocked in his horror thriller.