Clay Riddell (John Cusack) returns to his home when a pulse goes out, turning everyone who was on a cellphone into zombie killers, later dubbed “phoners”. Escaping the mass chaos this causes, he teams up with Tom (Samuel L. Jackson) and Alice (Isabelle Fuhrman), Clay’s neighbor; the group finds a house with guns and arm themselves. The group ends up at a private school where they meet the headmaster, Charles, and a student, Jordan. Charles escorts them to the school’s soccer field where the phoners have gathered and are sleeping. Using a watering truck, they douse the phoners with gasoline and set them ablaze, but the explosion kills Charles. Jordan joins the group, which then meets a group of normal people who offer them refuge for the night before heading to Kashwak, rumored to be a cell free area. In a bar, a woman in the group is transformed by analogue noise through the door, which she opens for the phoners, who attack. As the group escapes, Alice dies from her injuries sustained saving Tom in the attack, and is buried. The group stumbles upon a man and woman who are using the woman’s brother, a captive phoner, as a warning device for when flocks come near. Ray, the driver of an ice cream truck, tells the group Kashwak is a trap. Later, in a private conversation, Ray gives Clay a flip phone and a note with a phone number on it, telling him to use it in the end; Ray then commits suicide. The group arrives at Clay’s wife’s home, where Clay finds a message written on the fridge from his son saying he was going to Kashwak and that his mom is “1 of them”. In the attic, Clay finds his wife and is attacked by her, but is saved by Tom, and they manage to kill her. Clay goes on to Kashwak alone, and gives Jordan a can of yellow spray paint to mark a path on the roads and trees that he would follow once he got his son back. Clay arrives in Kashwak to find a massive cell tower being circled by a herd of phoners. He drives the ice cream truck to the center, shoots the lead phoner, and finds his son. The lead phoner is alive, emitting the pulse; the stampede also emits the same noise and his son begins to as well. Clay dials the number on the phone Ray gave him and remotely detonates the ice cream truck that had been loaded with C4. The explosion destroys the lead phoner and brings down the cell tower. Clay and his son find the yellow spray painted initials and follow the trail to Clay’s friends.