Hannah leaves a voicemail for her mother regarding a worrisome bite on her arm. A short time later, a screaming doppelganger of Hannah attacks the teen in her home.Best friends Zach Henderson and Randy Foster record a video tour of Multon, Missouri. While being interviewed, neighbor Mrs. Bissette points out thousands of unidentified insects crawling on vegetation.Zach and Randy also record Zach's crush Kayla Shepard playing soccer at their high school. Kayla introduces her father Larry, mother Beth, and little brother Joey.Zach and Randy go for a walk after having dinner with Zach's parents. Screaming draws the two boys back to Mrs. Bissette's house. Zach and Randy find Mrs. Bissette hiding in her closet with a bloody bite on her leg. A small creature breaks through the wall and scurries outside. Zach and Randy follow the creature and see it collected by Pastor Greg, who behaves robotically before being driven away.Zach and Randy show their strange video to Deputy Josh Haywood. Josh dismisses the footage as a probable prank.Zach and Randy confront Pastor Greg while he conducts a meeting with other robotic townspeople, including the sheriff. Pastor Greg denies being the person in the video and then bizarrely insults both boys' families.Zach and Randy return to Mrs. Bissette. Also behaving robotically, Mrs. Bissette denies being bitten by showing that her leg is fine. Zach and Randy flee after spying a classmate's father tied to Mrs. Bissette's bed.Zach and Randy show their footage to Zach's parents. Mr. and Mrs. Henderson discourage their son from getting involved in their neighbors' business.Kayla comes to Zach and Randy to tell them her father Larry is acting strangely. Zach and Randy tell Kayla about the odd behavior they have witnessed throughout town. Kayla asks for help getting her brother Joey away from Larry. The three teens see additional residents behaving weirdly while walking to Kayla's house.Kayla and Randy distract Larry while Zach searches for Kayla's mother Beth. Zach finds a large pod in the attic. Zach tells Kayla's brother to hide when he hears Larry coming upstairs.Zach runs to the bathroom to make it look as though he was only using the toilet. Zach finds Kayla's mother dead in a basket.After leaving the house, Zach, Randy, and Kayla take the new footage to Deputy Holloway. Josh goes to the Shepard house to investigate, but reverts to thinking Zach and Randy are creating a hoax when a replacement Beth appears as Kayla's mother. The three teens realize the escalating danger when they see Pastor Greg in the house alongside Joey.Thinking they can attract outside help, Zach, Randy, and Kayla try putting their footage online to expose the clone conspiracy. However, they find that their cellular signals are being jammed.The three teens go to Zach's parents for help, but discover a clone replaced Zach's dad. The clones trap Zach and Randy in a barn with two creatures. One of the creatures bites Randy. A doppelganger of Mrs. Henderson emerges from a pod to drain the lifeforce from Zach's real mother. Zach kills the clone by impaling her with a shovel. Kayla rescues the boys.Zach, Randy, and Kayla return to Josh once more. Josh shows the teens he killed his clone after it tried to attack him. Josh now believes the danger Zach and Randy tried warning him about.The group concludes that the creatures bite humans to acquire a genetic pattern and incubate a clone. The doubles then kill the original humans to acquire their memories and identities.Randy's clone comes to Josh's trailer trying to kill Randy. A horde of clones overturns the trailer with everyone inside. The horde pulls Josh away. Randy runs into the woods to draw the doubles to him so Zach and Kayla can escape.Zach and Kayla walk robotically to blend in with the clones as they make their way to Kayla's mother's store in town. While Zach retrieves a van key, Kayla becomes distracted when she sees her brother Joey being brought to a nearby fire station along with the rest of Multon's children.Kayla infiltrates a setup where replaced parents have creatures bite their children for cloning. Kayla gets captured when her presence is detected. Joey flees in the commotion. Zach comes to Kayla's rescue in the van.After driving away, Zach notices Kayla was bitten. Thousands of tiny bugs form into a creature that bites Zach.With the entire town transformed, Zach and Kayla formulate a plan to get to the cable company and upload their video there. Along the way, Zach and Kayla encounter Randy's double and drown him in shallow water.Zach and Kayla fight past Zach's double as they infiltrate the cable building. The two teens successfully upload their footage to the internet. Zach and Kayla kiss. The two teens then flee the facility after killing their doppelgangers by activating the carbon dioxide extinguisher system.Zach and Kayla reunite with Joey. However, they see on TV that the clones have taken over the world. Zach and Kayla realize their town was actually the last to be assimilated, not the first. Scattered survivors begin replying to their online video to organize a resistance.