A young man agrees to fulfil the ritualistic duties of a shomer and sit in vigil over a dead body, but realizes something is very wrong when he arrives at the dilapidated house. The plot unfolds over a single evening, set in a dilapidated house in Brooklyn's Hasidic Borough Park neighborhood. After arriving, Yakov begins to experience increasingly disturbing and frightening occurrences, which lead him to question his sanity and confront a malevolent spirit known as a Mazzik.