Night of the Devils is an Italian vampire thriller with a remarkably good pedigree. The script is based on The Wurdalak, a short story by no less than Leo Tolstoy. The central character is the patriarch of a wealthy family who fears that he will show up one day in vampire form. Should this happen, he warns his family not to let him back in his house, no matter how much he begs or cajoles. Not surprisingly, his warnings are to no avail. The filmmakers "improve" upon Tolstoy by adding liberal doses of sex. An earlier cinemadaptation of The Wurdalak, starring Boris Karloff, was incorporated into the omnibus 1963 melodrama Black Sabbath.
~ Hal Erickson, All Movie Guide