The film begins with a harrowing scene: an unidentified boy is coerced by a man in a black Nazi uniform to shoot a young woman in a secluded forest, while a mysterious figure looms in the background. The narrative then shifts focus to Yakov Ronen, a former Jew grappling with a traumatic past and facing financial struggles without a job. Soon, he is approached by Reb Shulem, a member of his past Orthodox Jewish community, who seeks Ronen's assistance to keep vigil over Rubin Litvak, a Holocaust survivor who has recently passed away. Shulem had previously hired a Shomer for this purpose, but that individual left in fear, leading Ronen to accept the job after negotiating for a higher fee.
Later that evening, Ronen meets with Litvak's widow, Mrs. Litvak, who is battling Alzheimer's disease. With reluctance, she allows Ronen to assume the role of Shomer, as Shulem informs him that the mortuary men will arrive in five hours. As Ronen begins the vigil, he becomes aware of eerie noises and catches sight of a shadowy figure in the dining room. He discovers a photograph of Litvak with his family, where a familiar shadowed figure lurks behind them. After briefly dozing off, Ronen experiences a nightmare featuring his younger brother being tormented by older men.
Upon waking, Ronen encounters more unsettling events—the lights flicker as he messages his girlfriend Sarah, and an inexplicable video appears on his phone, showing Mrs. Litvak approaching him while he sleeps. This video mysteriously vanishes moments later. During a conversation, Mrs. Litvak confides in Ronen about how her actions drove their children away. He later hears an unnerving recording in the basement, where Litvak reveals that he has been haunted by a Mazzik, a malevolent spirit, since his time in Buchenwald. The Mazzik feeds on the pain of a "broken person," and its true face must be revealed and burned by dawn on its first night.
Suddenly, the Mazzik manifests behind Ronen, prompting a terrified escape from the basement. He receives phone calls from both his physician, Dr. Kohlberg, and his deceased brother asking, "Why did you let me die?" In a moment of panic, Ronen rushes outside to find Shulem, even as Mrs. Litvak warns him of losing too much time in the house. Yet, as he walks, he suffers from intense cramps and encounters the Mazzik again. In a fright, he stumbles back into the house, only to have the Mazzik appear at the door, causing him to fall.
Through a series of flashbacks, we learn of Ronen's guilt over his brother's death in a car accident after fleeing his tormentors. With Mrs. Litvak's aid, Ronen confronts the Mazzik, which has taken on his own appearance. In a moment of resolve, he ignites its true face, ultimately banishing it after witnessing Litvak's body convulsing horrifically. A flashback reveals that Litvak himself was the boy forced to shoot the young woman, an act that ignited the Mazzik's attachment to him.
As dawn breaks, the mortuary men arrive to take Littak's body away. Shulem extends an invitation for Ronen to join him for morning prayers, but Ronen declines, stating, "Not today." As he exits the house, a dark figure—presumably the Mazzik—follows him down the street, suggesting that the ordeal is far from over.
