Craig Zobel’s polarising drama re-enacts and illuminates a vicious prank that took place repeatedly in a number of US fast-food chain stores. A middle-aged shop manager (Ann Dowd) takes a call from a police officer instructing her to detain a pretty young staff member accused of theft. During the course of a night various others are drawn into the methodical sexual humiliation of the young woman. Dowd gives the film its scarily vagrant heart: she is unnerving and unforgettable as the apologetic but dutiful jailer. You may forget you are watching acting, she is so credible in her wavering subservience to the voice of authority.