Repentinamente, em uma escola de uma pequena cidade no Ohio, os professores começam a agir estranhamente. Dois estudantes escondidos em um armário testemunham dois professores matando a enfermeira do colégio, mas logo a vítima aparece viva e eles logo concluem que algum alienígena está se apossando do corpos. Assim, o medo toma conta deles e de seus amigos, pois qualquer um pode ser dominado por este ser que ninguém sabe de onde veio, mas parece ter um objetivo definido: possuir todos os terrestres que surjam na sua frente.
Um alienígena (Scarlett Johansson) chega à Terra e começa a percorrer estradas desertas e paisagens vazias em busca de presas humanas. Sua principal arma é sua sexualidade voraz... Mas ao longo do processo, ela descobre uma inesperada porção de humanidade em si mesma.
When Environmental Protection Agency inspector Steve Malone travels to a remote military base in order to check for toxic materials, he brings his family along for the ride. After arriving at the base, his teenage daughter Marti befriends Jean Platt, daughter of the base's commander, General Platt. When people at the base begin acting strangely, Marti becomes convinced that they are slowly being replaced by plant-like aliens.
A young couple purchase their new home to start a life together, only to find out the elderly couple next door have other plans for them.
Edinburgh surgeon Dr. Robert Knox requires cadavers for his research into the functioning of the human body; local ne'er-do-wells Burke and Hare find ways to provide him with fresh specimens...
A bizarre visit with an estranged friend, an unexplained scar, and vivid, violent dreams of an ominous tunnel have Sandy worried something might not be right with her. As she begins to feel sick she becomes more and more paranoid that something is living inside her. Something that wants to become her.
Mona and her ex-girlfriend, Jules, broke up six months ago and they still can't manage to have a conversation that doesn't dissolve into an argument. It wouldn't be such a problem if they didn't work in neighboring retail shops and have to see each other every day. Meanwhile, something weird is going on with the residents of their small town. Some of them are getting sick, others are acting a little less human and a lot more like robots. Can Mona and Jules set aside their relationship drama long enough to avoid the body snatching invaders?
Summer, unhappy with her boyfriend, receives a mysterious email inviting her out to a spiritual obstacle course. Summer gathers her four friends, each battling a dilemma of their own, to drive to the Sedona Desert, where they are promised this “vortex” will improve their lives. They embark on these courses with the help of their uncanny guide Hermes, who leads them into a series of unusual practices. Little do they know they are being monitored by mysterious hooded entities, eager to take over their bodies.