Monsters are everywhere in Lovecraft Country.In HBO’s new period piece from writer-producer Misha Green (Underground), about a Black Korean War veteran trying to find his missing father in segregated America, monsters emerge from dark forests, they block open roads, they smash through windows and doors. Some have slimy, grayish skin, tentacles, razor-sharp teeth, and dozens of eyes. Others are human: cops enforcing sundown policies; white business owners who won’t serve Black people; white families who support the Ku Klux Klan and segregation, who prefer Black Americans to fall into three categories: servile, invisible, or dead. The word monster is flexibly defined, blurring the boundaries that tend to separate straight drama from science fiction and fantasy, and applying it to the main characters’ inner lives as well. In that, the show’s tone owes a lot to Rod Serling’s The Twilight Zone (“The Monsters Are Due on Maple Street” and “The Eye of the Beholder” in particular), which was recently rebooted by one of Lovecraft’s executive producers, horror maestro Jordan Peele.