Thorn (2014)

Four years ago, on February 29th, Jessica was a pretty, popular, high school girl with everything going for her when, on the eve of her sixteenth birthday, she and her friends faced a deadly nightmare when the local urban legend known only as Thorn became a terrifying reality. Thorn descends on her school in a massacre of blood and terror which she barely escapes with her life, if not her sanity, intact.