Valentine’s Day has had a long and fruitful collaboration with movie horror. Back in 1931, for instance, the Bela Lugosi version of Dracula, arguably the original American horror movie, was nationally released on February 14, as “the story of the strangest passion the world has ever known!” Later came the 1981 slasher movie My Bloody Valentine and its 2009 remake, and the 1982 X-Ray with Barbie Benton (originally titled Be My Valentine, or Else), the 2000 Lover’s Lane and Valentine in 2001. All of these exercises...