| Director | Chad Archibald |
|---|
Casey (Elma Begovic) celebrates her bachelorette party with her friends Kirsten and Jill in Costa Rica. She is second-guessing her impending wedding to her fiancé Jared Kennedy and is exasperated with Jared's mother, who happens to be Casey’s landlord. Casey gets bitten by an insect at one point during the trip but is too preoccupied to take notice, brushing it off as an ordinary bug bite. After returning home, her body begins to mutate gradually, her senses become abnormally acute, she can no longer tolerate the taste of food, and she is plagued by nightmares. When she wakes up one day, she finds there are insect eggs all over her apartment. Jared's mother invades Casey's apartment to angrily challenge her about her plans to marry her son, but Casey kills her when she instinctively spits acid into her face during an argument. Noticing she hasn't seen Casey for days, Kirsten becomes very worried and visits her, but Casey ends up killing her as well when she finds the body of Mrs. Kennedy and panics.
It is revealed that Jill is in love with Jared and deeply resents Casey for being engaged to him. In reality, she has been attempting to sabotage their relationship since Costa Rica, where she stole Casey’s engagement ring and got her drunk so she'd sleep with other men at the party (which Jill recorded to make it look like Casey cheated on him). Jill shows Jared the footage and seduces him. Thanks to her heightened senses, Casey hears the two as they have sex in Jill's car and becomes enraged. Later, when Jill enters Casey's apartment, she is overpowered and tied to a chair. When she wakes up, a heavily transformed Casey forces her to watch more of the footage, revealing that she had recorded one of the men taking Casey to his room to rape her after she'd become too drunk to fight back. After confronting Jill about her betrayal, Casey forces her to call for Jared, who then rushes into the apartment. Casey kills Jill in front of him, and the two begin to fight. Although Jared is able to impale Casey, he is gravely injured when she uses her newly-grown tail to sting him. He drags himself back to his apartment and tries to make an emergency call, but fails.
A week later, the entire building has been quarantined. The police raid the house and find the bodies of Mrs. Kennedy, Jill, and Kirsten in Casey's apartment. They also find Jared in his own apartment, seriously injured and already mutated into some kind of human cocoon. When they try to help him, a massive swarm of insects hatch from the eggs in his body and attack the police. At the end of the film, two joggers are talking about an upcoming trip to Costa Rica. One of them is bitten by one of the newly-hatched insects, but she dismisses it as "just a bite".