The story is set in a town called Bridgton, Maine. After a thunderstorm, a very thick supernatural fog covers the small town. A large group of people that are barricaded inside of a grocery store quickly realizes that the mist harbors dangerous predators not of this earth. The people become increasingly panicked and turn to a religious zealot who believes that it is the end of days and human sacrifice is the only solution. A small group of rational skeptics realize that escape into the mist may be the only way they can survive.
The morning after a severe thunderstorm, an unnaturally thick mist gradually envelopes the small town of Bridgton, Maine. Artist David Drayton, along with his son Billy and neighbor Brent Norton go to the local supermarket for groceries. Upon arrival, their suspicions are aroused by the sound of a siren. The mist completely covers the supermarket and conceals strange and hostile creatures. The situation is aggravated by an earthquake, which damages communications and leaves the store without electricity. When a young bagger, Norm, goes outside to fix a clogged vent in the store's generator, he is dragged into the mist by tentacles.
David and assistant manager Ollie Weeks witness Norm's death and try to convince the remaining survivors of what has happened, imploring that no one leave the store. Norton and a small group of people accuse David of lying and go outside for help, only to be killed by a huge creature. Ollie is given a revolver by the young Amanda Dumfries. Later, pterosaur-like creatures fly into the store and are killed by improvised means. Two soldiers from a nearby military base reveal that the mist may be associated with "Project Arrowhead" – in which they were involved – before committing suicide. David leads a group of people to obtain medical supplies from an adjacent pharmacy, where they encounter huge spiders. In the wake of mass hysteria among the survivors, religious fanatic Mrs. Carmody convinces them that the current events fulfill a biblical prophecy of the end time, and believes that human sacrifice is required to save themselves from God's wrath.
Later, David, Billy, Ollie, Amanda and a few other survivors attempt to break out of the store, but are thwarted by Mrs. Carmody, who convinces the crowd to offer Billy and Amanda as sacrifices. Ollie shoots Mrs. Carmody and dissolves her congregation. En route to David's car, Ollie and one other survivor are killed, while another flees back to the store. The group attempts to reach David's house, but the roads to it are either blocked or damaged. On the radio, through the interference, David hears of Hartford, and he drives on in the hope of an escape from the mist.
- David Drayton - Painter
- Billy Drayton - David Drayton's son
- Stephanie Drayton - David's wife and Billy's mother
- Mrs Carmody - Antiques shop owner and religious zealot
- Brenton Norton - Lawyer
- Ambrose Cornell
- Bud Brown - Manager at Federal Foods Company
- Ollie Weeks - Assistant manager at Federal Foods Company
- Myron LaFleur
- Mike Hatlen
- Hilda Reppler - Teacher
- Hattie Truman
- Buddy Eagleton
- Mr McVey - Butcher at Federal Foods Company
- Terrell Jermaine Boyd - bag boy at Federal Foods Company
- Jim Grondin
- Amanda Dumfries
- Dan Miller
- Sally - Clerk at Federal Foods Company
Creatures in the mist
- Gray Widowers
- Killer Kite
- Green Dragonfly