Renowned criminologist and occult investigator, William Sebastian recruits his old friend, Dr. Hamilton to assist in his current case. Anitra Cyon - sister of prominent British businessman Geoffrey Cyon, believes her brother's dabbling in the black arts. In turn, Geoffrey claims she's mentally unfit. Sebastian and Hamilton travel to the Cyon estate to investigate the matter. Complicating the issue is Sebastian's debilitating heart condition which was induced by his own experimentations with the black arts.