On Christmas Eve in an unnamed suburbia, 17-year-old Ashley (Olivia DeJonge) is busy babysitting the precocious 12-year-old Luke Lerner (Levi Miller). Luke has romantic feelings for Ashley and attempts unsuccessfully to seduce her while watching a horror movie. Strange happenings outside put Ashley on edge, but it ultimately appears to be just Luke's best friend, Garrett (Ed Oxenbould) who has stopped by to hang out. Hearing a window break upstairs, the trio find a brick inscribed with "U leave and U die." Garrett panics and runs out the back door, but is apparently killed by an unknown shooter.Shocked, Ashley and Luke run upstairs and hide in the attic. Ashley almost breaks her neck from a fall but Luke catches her. After they run into Luke's room and hide in his closet, a masked intruder armed with a shotgun walks into the room. Ashley recognizes the mask as one of Luke's and yanks it off the intruder, revealing Garrett. Ashley realizes that Luke was planning to further seduce her by scaring her. Angered, Ashley slanders Luke, calling him mental and saying he needs therapy, and tries to leave. While at the top of the stairs, Luke slaps her with his gun, causing her fall down the stairs and be knocked unconscious.Luke binds Ashley with duct tape, then forces her to play truth or dare. A little later, Ashley's boyfriend, Ricky (Aleks Mikic), arrives at the house after receiving a text message sent by Ashley earlier. When Ricky fails to find Ashley, he realizes that something is wrong. Luke tries to knock him out, but fails. After nearly killing Luke, Ricky is threatened by Garrett with the shotgun. Luke knocks him out and they tie him up beside Ashley.While Ashley uses a shard of glass to cut her binds, Luke tries to show Garrett what happens if you actually hit someone in the head with a swinging paint can similar to the scene from Home Alone. Luke tries to demonstrate with Ricky, but misses on the first swing. Ashley gets free and threatens Luke with a pistol. He drops the paint can and kills Ricky. When Ashley realizes the gun is unloaded, she tries to escape to a group of carolers outside. Luke uses the brick tossed through the upstairs window to knock her out again before she can alert them.After tying up Ashley again, Luke calls Ashley's ex-boyfriend, Jeremy (Dacre Montgomery) to come over to the house, claiming that she wants him to write an apology letter. While Jeremy does so, Luke hangs him from a tree, making the apology look like a suicide note. He kills Garrett for trying to free Ashley. Luke then stabs Ashley in the neck and stages the scene to frame Jeremy for the killings. Later, he goes to bed and waits for the return of his parents, who contact the police when the find the bodies. It is then revealed that Ashley stuck duct tape over the stab wound to stop the bleeding. Luke watches from his bedroom window as Ashley gives him the finger before being wheeled into the ambulance... thus making a lucky escape.In a mid-credit scene, the evil and scheming Luke tells his mom that he is worried about Ashley and wants to go to the hospital (to presumably try another chance to kill her).
Storyline
When you think "suburbs," you think "safety," but this holiday night the suburbs are anything but safe. Ashley (Olivia DeJonge) thought this babysitting job would be an easy night, but the night takes a turn when dangerous intruders break in and terrorize her and Luke (Levi Miller), the 12-year-old she's watching. Ashley defends her charge to the best of her ability only to discover this is no normal home invasion.