Blood Night: The Legend of Mary Hatchet (2009) on Netflix

Plot summary

In 1978, Mary Mattock murders her parents with a hatchet and is found mentally unfit, so she is placed in Kings Park Psychiatric Center. Her story becomes local folklore, and youngsters in the area mark Blood Night in her name each year. In 2008, a group of teenagers hold a séance at her grave in a cemetery on Sweet Hollow Road in Huntington. Gus, the caretaker and a former employee of the psychiatric center, tells them that Mary will keep killing until she finds her child, whose grave lies near Kings Park. The teenagers move on to a house party, where stragglers are killed by an unseen murderer.