Clayton Riddell, a struggling artist from Maine who is estranged from his wife, Sharon, and his young son, Johnny, has landed a graphic novel deal in Boston. As he prepares to celebrate, somebody, somewhere, triggers "The Pulse," a signal sent out over the global cell phone network that instantly turns all cell phone users into bloodthirsty, homicidal creatures. Civilization crumbles as the Pulse's victims – dubbed "phone crazies" or simply "phoners" – attack each other or any unaltered people in view.
- Clayton Riddell: a graphic artist separated from his family in Boston as the Pulse destroys civilization. Clay heads north with a group of survivors and tries to find his son, Johnny.
- Tom McCourt: a middle-aged, gay man from Malden, Massachusetts, Tom teams up with Clay in the initial chaos created by the Pulse. With Clay and Alice, he travels to his home in Malden. Then, they move on north where they meet others. He remains with the group until after Kashwak when he survives and leaves Clay along with Jordan, Denise and Dan.
- Alice Maxwell: a 15-year-old girl, Alice teams up with Clay and Tom to head north. She forces her anxiety and trauma into an abandoned child's Nike shoe which helps her cope with the atrocities committed by the phoners. Alice remains an important part of the group.
- Jordan: a 12-year-old-boy studying at prep school that was devastated by the Pulse, Jordan faithfully remains with the headmaster, Charles Ardai, until they destroy the flock at the school and Ardai is driven to suicide by the phoners. Jordan remains with the group and provides the intellectual theory and comparison of the effects of the Pulse to that of a worm in a computer.
- Charles Ardai: the headmaster of Jordan's prep school, Ardai is a father figure to Jordan and cares for the group. They manage to destroy a flock of phoners, but then Ardai is telepathically forced to commit suicide.
- Dan: a survivor and part of another flock killing group, Dan is intelligent and joins the group as they head to Kashwak. He ultimately survives and leaves Clay with Jordan, Denise and Tom.
- Denise: a pregnant survivor and part of another flock killing group, Denise joins the group with Dan and Ray and ultimately survives with them. She is described by Clay as a strong-willed woman and leaves her with Tom, Jordan and Dan after Kashwak.
- Ray Huizenga: a construction worker who specialized in explosives, Ray was one of the flock killers with Dan and Denise but has a plan regarding Kashwak. He gives Clay vague instructions about the plan before committing suicide with a pistol in order to mask his plans from the phoners. This ultimately saves the entire group.
- The Raggedy Man/President of Harvard: the main antagonist of the book, he wears a torn red Harvard hoodie. He is killed by the bomb at Kashwak.
- "Pixie Light": a teenage girl spotted by Clay in Boston and dubbed Pixie Light because of her haircut and hair color, this girl was one of the first victims of the Pulse and attacked another phoner seconds after listening to the Pulse on her cell phone. Pixie Light tore out the phoner's neck with her teeth and was knocked unconscious by Clay before she could do any more harm and was left on the streets of Boston.
- "Pixie Dark": a teenage girl spotted by Clay in Boston who was named for reasons similar to Pixie Light, Pixie Dark was Pixie Light's friend and only heard a small dose of the Pulse via Pixie Light's cell phone. Instead of going completely crazy like her friend, Pixie Dark's brain was erased by the Pulse and she lost her mind, running off in Boston shouting "Who am I?". She is referenced several times throughout the book by Clay.
A role in the story was offered to the winner of a charity auction sponsored by ebay.
"One (and only one) character name in a novel called CELL, which is now in work and which will appear in either 2007 or 2008. Buyer should be aware that CELL is a violent piece of work, which comes complete with zombies set in motion by bad cell phone signals that destroy the brain. Like cheap whiskey, it's very nasty and extremely satisfying. Character can be male or female, but a buyer who wants to die must in this case be female. In any case, I'll require physical description of auction winner, including any nickname (can be made up, I don't give a rip)."
Other authors like Peter Straub also participated in the online auction, selling roles in their upcoming books. The King auction ran between September 8 and 18, 2005 and the winner, a Fort Lauderdale, Florida woman named Pam Alexander, paid over $25,000. Ms. Alexander gave the honor as a gift to her brother Ray Huizenga; his name was given to one of the zombie-slaughtering "flock killers" in the story, a construction worker who specializes in explosives, but then later commits suicide in the aid of the "flock killers" escape.
The book generally received good reviews from critics. Publishers Weekly described it as "a glib, technophobic but compelling look at the end of civilization" and full of "jaunty and witty" sociological observations. Stephen King scholar Bev Vincent said "It's a dark, gritty, pessimistic novel in many ways and stands in stark contrast to the fundamental optimism of The Stand.