Hannah leaves a worrisome voicemail for her mother regarding a bite on her arm, but soon after, she is attacked in her home by a screaming doppelganger. Meanwhile, best friends Zach Henderson and Randy Foster are busy recording a video tour of their hometown, Multon, Missouri. During their interview with neighbor Mrs. Bissette, she points out the multitude of unidentified insects crawling across the vegetation, raising concerns.
Complications arise as Zach’s crush, Kayla Shepard, is introduced along with her family, including her father Larry, mother Beth, and little brother Joey. After a family dinner, Zach and Randy hear a scream and rush back to Mrs. Bissette’s house, only to find her hiding in a closet with a bloody bite on her leg. Suddenly, a creature bursts through the wall, leading them to follow it outside, where they encounter Pastor Greg exhibiting robotic behavior.
After they present their unusual recording to Deputy Josh Haywood, he dismisses their claims as mere prank material. Concerned, Zach and Randy confront Pastor Greg and witness a meeting with other townsfolk displaying similarly strange behavior, prompting them to return to Mrs. Bissette. She too shows signs of robotic behavior, denying her injuries when questioned, which solidifies Zach and Randy's suspicion of a deeper issue at play.
Determined to uncover the truth, the duo reveals the strange events to Zach's parents, but they are advised to stay out of their neighbors' affairs. The situation escalates as Kayla confides in Zach and Randy about her father’s odd behavior. Together, they observe more residents’ unsettling actions while en route to Kayla’s home. Together, they attempt to distract Larry while Zach searches for Kayla’s mother in the attic, leading to the horrifying discovery of her lifeless body.
Seeking assistance, the three teens bring their findings back to Deputy Holloway, only to find further confirmation of their fears when a clone impersonates Kayla’s mother. The true danger strikes as they witness Pastor Greg in the house with Joey, motivating them to stream their footage online in hopes of attracting help. Unfortunately, their efforts are thwarted when they discover their cellular signals are jammed.
In a desperate attempt for help, they go to Zach's parents only to find that a clone has replaced his father. Trapped with two creatures in a barn, Randy suffers a bite, and chaos ensues when a doppelganger of Mrs. Henderson emerges from a pod, seeking to drain Zach's real mother’s lifeforce. In a moment of desperation, Zach impales the clone with a shovel, and Kayla aids in their escape.
Returning to Josh, they share their experiences, where he reveals he had also dealt with a clone of his own. The group realizes that these creatures bite humans to replicate their genetic patterns and subsequently murder them to assume their identities. The tension peaks when Randy’s clone confronts them, leading to a struggle in Josh's trailer before they manage to escape into the woods.
In a bid to blend in with the clones, Zach and Kayla navigate carefully toward Kayla’s mother's store. Once there, Kayla is appalled to see Joey among those being captured for cloning. Amid the chaos, she is caught, but Joey manages to flee. Zach comes to her rescue using a van, only to find out that Kayla has been bitten during their escape.
With the entire town transformed into clones, Zach and Kayla devise a plan to upload their video to the cable company. After a fierce confrontation with Randy's double, they drown him and push through their own doppelgangers at the cable building. They successfully upload their footage, and after sharing a kiss, they flee, killing their clones using the carbon dioxide extinguishing system.
Upon regrouping with Joey, they are horrified to learn through the news that the clones have now taken control of the world. It dawns on Zach and Kayla that their town was merely the last to fall victim to this takeover, rather than the first. However, hope flickers as scattered survivors begin responding to their online video, seeking to organize a resistance against the clones.
