While on the phone with his girlfriend Jill (Ashley Hinshaw), who has moved away to attend college, David (Rhys Wakefield) prompts her to explicitly wish that he were there to see her compete in a fencing tournament, only to surprise her with an unplanned visit. After the competition, David approaches Jill's similarly attired opponent (Hannah Kasulka) from behind and flirts with her, thinking she is his girlfriend. Intrigued, she kisses David, and Jill storms off angrily after walking in on them. Later, David meets with his friend and roommate Teddy (Logan Miller), a sex-obsessed student who tells him that Jill will attend a house party later. Hoping that she will speak with him in person, David decides to attend the party, too.At nightfall, David and Teddy drive over to the large house where Angad (Rohan Kymal) is hosting the party in his parents house. Dozens of people are already there, drinking, partying, smoking dope, and other wild things.Meanwhile, a strange meteor lands near the site of the party, and electrical arcs cause a momentary blackout. The wild revelers do not notice brief, anomalous phenomena that occur during the blackout, such as a mirror image out of sync, but a drug dealer's girlfriend outside the party becomes spooked.As the raucous party proceeds, David searches the house for Jill, and Teddy attempts to charm Melanie (Natalie Hall) a very attractive blond student. To Teddy's surprise, Melanie invites him to join her upstairs in ten minutes. Meanwhile, David spies on Jill as she flirts with a friend. Elsewhere, Allison (Colleen Dengel), an outsider, unsuccessfully attempts to fit in. David attempts to apologize to Jill, but she becomes more angry with his fumbled apology and says that he makes her feel replaceable. When a small fire starts caused by a flying tennis ball, the sprinklers put out the fire. So, Angrad moves the party outside, and the house empties except for David, Teddy, Allison, and Melanie.When Teddy joins Melanie upstairs, he finds her naked on a bed. They proceed to have sex, and she steps into the shower afterward. During a second blackout, a duplicate of Melanie appears on the bed, surprised to find Teddy in the room. When the original Melanie exits the shower, the two Melanies come face-to-face, and Teddy flees the room in a panic.David confirms that the house has filled with duplicates of the party-goers, who repeat the actions their originals took ten minutes ago. Outside, the drug dealer Kyle (Adam David Thompson) and his duplicate get into a violent confrontation, and David watches as one of them murders the other. Worried that the duplicates may be hostile, the originals attempt to hide. Eventually, the duplicates disappear when another blackout happens due to the strange supernatural event.With each blackout, the duplicates momentarily reappear and reenact increasingly more recent actions. David becomes convinced that he can save his relationship if he crafts a better apology to Jill's duplicate. At the same time, Allison befriends her duplicate (Suzanne Dengel). Also, Teddy accidentally ruins the rendez-vous between his and Melanie's duplicates.Teddy runs outside and warns the other partygoers that his duplicate will now become belligerent, and he convinces the party-goers, most of whom are still skeptical, to hide from their duplicates in a pool house. When the duplicates reappear, David knocks his own duplicate unconscious and charms Jill's duplicate, and Teddy's duplicate attempts to convince the skeptical crowd of duplicates to attack the originals.Worried about their safety, several of the originals sneak out and murder their duplicates, which turns the enraged duplicates hostile. The originals retreat back to the pool house, and the duplicates lay siege. The next blackout causes the duplicates to appear inside the pool house. The crowded room erupts in violence, and several people die, including Teddy.David tracks down the original Jill, who had wandered back to the house, and he murders her so that he can be with her duplicate. In the meantime, the narcissist Allison seduces her duplicate, and they share a kiss.The final blackout causes the duplicates and originals to merge. David and Jill leave together and make their way to the pool house and have a make-out session. The confused party-goers stagger out of the pool house, and they begin to disperse. In the final shot, two meteors, like the original, are shown passing through the sky and appear to be leaving Earth.