Rebecca Hall delivers a powerhouse performance in a period ghost story that’s artful, atmospheric and downright scary. It’s set in the 1920s, in a English boarding school that occupies a haunted country manor. A boy’s ghost stalks the halls, terrifying the students, and after another boy dies mysteriously the school summons ghostbuster Florence Cathcart (Hall), a celebrated author who has made her career debunking apparitions. All but one of the students go home for the holidays, leaving Florence to rattle around alone with classic set of characters—a dashing schoolmaster/war hero (Dominic West), a steely matron (Imelda Staunton), a hollow-eyed student, and a creepy groundskeeper. It soon becomes clear that Florence’s scientific skepticism is a defense against her own deep-seated fears. And as she sets out her maze of sleuth-ware—trip wires, cameras, recorders and powders—the narrative lays its own elaborate traps. This feature debut from Nick Murphy does a better job building suspense than wrapping the plot with a brain-teasing rationale. But along the way, it delivers some real chills.