คำอธิบาย : Tyler (Taylor John Smith) is a 17-year-old high school student in love with his girlfriend Alision 'Ali' (Halston Sage). One night at a party, Tyler discovers before Ali moved to their school, she was a heavy partier and would often drink and sleep around. Tyler gets angry and they break up. Outside the party, he meets mysterious Holly (Bella Thorne). They end up partying and sleeping together. They spend the rest of the weekend in Holly's huge house, with Holly telling Tyler her father died and her stepmom travels a lot. Tyler says that the weekend was special before leaving, seemingly forgetting all about Holly. Tyler gets back together with Ali the following day, and while at school, notices Holly. Holly reveals that she goes there now and wanted to surprise him. Tyler tries cutting ties with Holly multiple times, but failing each time. Holly starts hanging out with Ali and her friend Lydia. Lydia starts becoming suspicious of Holly when she sees no social media presence. Holly gives Lydia the wrong smoothie on purpose, causing an allergic reaction that puts her in the hospital. Tyler starts suspecting that Holly is dangerous, especially when meeting her stepmom, Corrine, who reveals that she takes medication and Holly lied to him about where she's from. Holly tells Ali that she's pregnant, but not in contact with the guy who did it. Tyler asks Holly what she wants from him, to which she responds for them to be together. While trying to sneak up on Tyler, he knocks her down, causing her lip to bleed. Holly tells Ali that she and Tyler slept together the night before he decides to tell her. Ali says she never wants to talk to him again. Holly gets Tyler suspended, saying that he assaulted her. Tyler finds out that Holly's real name is Elizabeth. He looks her up online and discovers that she assaulted a student over a boy, and went to a mental institution for a while. That night, when Ali's parents leave, Holly knocks her out. When Ali doesn't respond to Tyler's texts, he starts to suspect Holly and starts driving over to her house. Ali awakens to discover she's tied up and bound to a chair in Holly's house and Holly lied about being pregnant. Corrine comes home and while trying to untie Ali, Holly sneaks up behind her and suffocates her with a plastic bag, killing her. When Tyler arrives, he sees Holly sitting in front of the fireplace, the first place he saw her the morning he woke up in her house previously. Holly tries recreating the weekend as Tyler runs around the house looking for Ali. He discovers Ali unconscious tied mid-air to the ceiling, forehead bleeding. He lowers her down, wakes her up, grabs a fire poker and starts trying to escape the house as Holly goes to get her gun. Tyler and Ali make it outside and before they get away, Holly stops them at gunpoint. Tyler tells Holly that he loves Ali and not her and he never will. Holly shoots Tyler in the shoulder as Ali picks up the fire poker and stabs Holly in the side, causing Holly to fall back into the pool. Holly is wheeled into the back of an ambulance, and asking the paramedic man to never leave her, implying she'll be obsessed with him. The film ends with Tyler, Ali and Lydia having fun at Tyler's little sister's birthday party.