THE FOLLOWING IS NOT COMPOSED BY ME. THIS APPEARS IN ONE OF THE MOVIE SPOILER WEBSITES AND IS WRITTEN BY SOMEONE CALLED 'John C'. ITS SO DESCRIPTIVE AND FANTASTIC THAT I DECIDED TO SHARE IT WITH OTHER IMDB USERS. THE TEXT HAS NOT BEEN CHANGED IN ANY WAY AND APPEARS EXACTLY AS WRITTEN BY THE ORIGINAL WRITER.
The movie begins with David Drayton (Thomas Jane), the main character, hand painting a movie poster for an upcoming film. A collection of his other original works, including a poster of The Thing can be seen in his studio. That night, a massive storm strikes Bridgton, Maine, the setting of the story, and his house loses power and a tree smashes through his studio window, ruining his latest painting. The next morning David, his eight-year-old son Billy (Nathan Gamble), and wife Steff (Kelly Collins Lintz) are cleaning up debris and assessing damage from the storm. Outside, the family notices a thick mist approaching from off the nearby lake. In the storm, the Drayton family boathouse has been crush by a fallen tree from their neighbors house. They go to the neighbor, Brent Norton (Andre Braugher), who is a lawyer, to exchange insurance information about the boathouse. David notices that Brent's Mercedes convertible has been smashed by a falling tree. Brent asks David if he will be driving into town to pick up food and supplies and if he could get a ride seeing as the storm claimed his car. David says yes and David, Billy, and Brent drive to town in David's SUV for the grocery store. David's wife, Steff, remains behind at the house. While driving to the supermarket they view several electric company trucks heading in the other direction, and oddly, several dozen military vehicles heading to the military base. David says to Brent if he's ever heard of all the crazy conspiracy stories about the military base and project arrowhead. Brent just laughs.
Upon arriving at the supermarket they find the store to be packed with people also stocking up on supplies. Three military men in the store are on leave. The soldiers are approached by a Military Policeman (Eric Kelly McFarland) to return to base and they their leave has been suspended and they have thirty minutes to finish shopping. After a minute elapses from the time David, Billy and Brent enter the store, a man, Jeff Miller, a local townsperson, flies into the market, bloodied and frantic. The man immediately begins screaming about something hidden in the mist that is attacking and killing people. Everyone looks outside, and the mist has now completely surrounded the grocery store and nothing can be seen outside of the store but white smoke. Several people flee the store immediately and screams are heard shortly after coming from outside. Jeff tells everyone to seal the doorway to the store and to remain inside. However, there is a lady (Melissa Suzanne McBride) who worries that she's left her two young children on their own at home. She wants to leave the supermarket to go home to check on them, and asks everybody to volunteer to accompany her. Nobody volunteers, so she leaves the supermarket on her own.
David meanwhile realizes already that they will be spending the next several hours, if not days in the store, and goes to the back of the store to check the generator. In the backroom of the store where the generator is, the loading dock, he hears something outside of the large loading dock door. Eventually the thing, the creature, starts pressing heavily into the door and he runs back into the main store. He tells three men a young male worker what he heard through the door and they dont believe him. David also tells him that the generator is smoking and might not work for that much long if it is not fixed. The five of them go back to the loading dock in the back of the store to fix the generator.
They conclude that the generators exhaust system is clogged outside and that someone must physically remove wha'ts unclogging the generator. A young bagboy of the grocery store, Norm (Chris Owen), volunteers to go outside. David warns and pleads for no one to go outside. Norm and the other men ignore the warnings and open the large loading dock garage door. Upon opening the door the mist has become incredibly thick and begins slowly entering the loading dock. Before anyone can react, a large tentacle snags Norms leg and pulls him under the door. He grabs the door and David pulls him back into the loading dock. Unfortunately several more tentacles follow Norm back into the loading dock and begin ripping flesh from his body. Bloodied and terrified Norm is dragged outside into the mist. David quickly grabs an axe and manages to chop off the end of one of the tentacles. They close the loading dock doorway. The mist concealed what the tentacles were connected to. The generator is still clogged.
The men are in shock and go back into the grocery to tell Brent what they've discovered, and to ask him if he has any idea what to do. Brent however lashes out at them, believing they are playing a joke on him by saying that monsters are dwelling in the mist. Brent believes that some of the townspeople are setting him up for a prank, a joke, and that no monsters exist. Brent says that he knows it's just a storm and that trying to joke about monsters is not going to work on him. He says that the men are trying to prank him because he was the lawyer who represented people who sued this grocery store and lost. David and the men though show Brent and several others the piece of tentacle that David had severed from the monster. Brent has already made up his mind though, and he says that it proves nothing and that the mist is nothing more than part of a storm.
Brent organizes a group of people to leave the store to drive and find help, reassuring them that nothing is going to happen if they leave the store into the mist. One man says that when Brent and his group leave, he will go to the parking lot and retrieve a shotgun from another mans car who is to afraid to retrieve the gun himself, and he will bring the gun back into the store. David asks the man to tie a 300 foot rope around his waist, so that the people in the store will know that he made it at least as far as the rope goes. Brent and his group leave first. The man with the rope leaves right behind them. After a minute of silence, waiting for the man to come back with the shotgun, his rope begins pulling rapidly out of the store. David and several others try to hang on but suffer rope burn. Finally the rope stops pulling and David and the other pull on the rope. Eventually the rope starts coming back into the store red, covered in fresh dripping blood, and everyone in the store begins crying and screaming. The lower, severed half, of the mans body is still attached to the end of the rope. They decide not to pull the torso in and let it rest in front of the store. The remaining people assume that Brent and his group have also died and they realize the only way to survive is barricade everything in front of the storefront. One of the store supervisors observes the entire front of the store is large glass windows. The supervisor, Ollie Weeks (Toby Jones), organizes all of the dog food and fertilizer to be stacked up. The wall is only five feet tall and the remaining three feet of glass is exposed.
Since the moment that they've been trapped in the store, the people have been split into two groups. One groups follows David and Ollie, and believe that the group must barricade the doorway and survive until help comes. The second group however listens to a deeply religious woman, Ms. Carmody (Marcia Gay Harden), who believes that God has sent down his plagues and wraths upon their town and the world for their sins. Ms. Carmody slowly convinces many people that God is angry at the sins of the world and has seen down monsters and demons in the mist to claim all those are not worthy of salvation. She cries out that she's a righteous follower of God and that anyone who wanted to be saved should listen to her words and scripture. David and several others are convinced that this is not a biblical problem and that it can be rationally solved.
Both groups don't have a chance to argue that night though, as giant, two feet long insects begin landing on the windows of the stores front. The insects though are not the problem; its the giant six feet pterodactyl like predator birds that are now crashing into the windows that are alarming. The birds are killing the insects, but whenever a bird crashes into an insect resting on a window the windows crack further. Eventually a bird shatters a window cleanly, allowing several insects to fly through the window. The insects attack and kill only a young girl, who is a worker of the grocery store and also a love interest of one of the military personnel, Private Jessup (Sam Witwer). The people use shovels, rakes, and sticks to beat and kill the insects, but two large bird creatures also enter the store. The first bird kills a man immediately upon entering the store and is in turn killed by being set on fire. The other bird is shot by Ollie who wields a six shooter pistol. The fire used to kill the bird though also severely burns a man. He is burned so badly that he says that the pain is unbearable, and begs to be killed so end his suffering. David and those watching the burn victim tell him to hang on a little longer.
David and his group set out to outside go to a nearby pharmacy in the shopping plaza to retrieve burn medicine, antibiotics, and painkillers for the burn victim. Jessup sees the group leaving the store and volunteers also. On the mission they encounter the Military Policeman who ordered the three military soldiers on leave to return to duty. The MP has been strung up in a spiders web and has large pulsing sores covering his body. Coughing and stuttering, he says that everything is our fault and that the military is responsible. The sores on his body then open up to reveal live spiders growing inside of them. David and his group see the source of the smaller spiders, several large three feet long spiders and begin to retreat back to the grocery store. In the retreat they lose two people to the spiders. The large spiders have claws and fangs, but also shoot acidic webbing. One man dies from the webbing burning through his jeans and flesh, eventually bleeding to death. The other victim is surrounded and attacked by spiders and killed.
David and his group make it back to the store ask the soldier who came with them on the mission what the MP meant by it being the military's fault. The soldier says his two other soldiers who are in the store can explain it better, but the group discovers that the two other soldiers have committed suicide by hanging themselves in the loading docks. The remaining soldier says that all he knows was that scientists had found a way to open up doorways to other worlds and dimensions and they called it Project Arrowhead. This is all revealed to the remaining survivors in the store. Ms. Carmody says that the doorway was hell and that now we are paying for the soldiers' mistakes. She demands that the remaining soldier be sacrificed for his sins, for bringing these monster here. She says that God demands his blood. The soldier pleads that he was just a lowly solider and the scientists were the ones who did all of the experimenting. Ms. Carmody exclaims that we have tampered with God's power, we have split God's atoms, used God's stem cells and allowed abortions and now those responsible must suffer. One of the men who has sided with her, lunges and stabs the soldier three times in the stomach. To David and his groups horror, the soldier is tossed through the front door to the outside. Bleeding and alive, he begs to be let back inside. A gigantic monster approaches the store and grabs the soldier and kills him. The monster leaves and Ms. Carmody says that the monster has been appeased tonight, but more people must be offered up eventually.
Ms. Carmody's biblical ramblings become more fervent and frequent. She starts talking commandingly about a human sacrifice. David assembles several people, to accompany him, because he intends to break out of the store and see if he can drive through the mist and find a place where the mist is not there. David, his son, Ollie, and six others agree that in a couple nights they will leave after stockpiling food and supplies under the radar of Ms. Carmody and her group. The night of the departure Ms. Carmody catches them before they can leave and assembles everyone else in the store to prevent them from leaving. David tells her to move but she counters by saying that not only can David not leave the store, but that David's son Billy, must be the next sacrifice. David and Ollie are approached by several men armed with knives. Ollie doesn't hesitate though and opens fire on Ms. Carmody with his pistol. He shoots her in the stomach, stunning her followers, and then he executes her with a bullet to the forehead, completely horrifying them and causing them and back off. Ollie points the gun at the knife-wielding men, causing them to retreat, and motions for David and the group to make a break for it. On their way out, a furious woman, who was a very ardent follower and appeared to have had a very close friendship with Mrs. Carmody, screams at Ollie, calling him a murderer, and approaches the group, intent on killing Billy herself in order to avenge Mrs. Carmody, but runs off in terror when Ollie points the gun at her.
David and the group get outside and run for David's SUV. One of the men falls and is helped by two other men. Two of them are attacked and killed by spiders and the other runs back to the market and is welcomed inside. Ollie reaches the SUV first but is killed by the giant creature that killed the soldier from before. David, his son Billy, a woman, the original man who warned of the creatures in the mist, and an older woman, eventually make it into the SUV. David, before driving away sees the gun that Ollie dropped, and grabs it off the hood of his car while a giant spider climbs on the car. David starts the car and drives by the front of the store while the survivors that followed Ms. Carmody, who have now snapped back to reality and realize what they had done, watch him drive by.
David, his son, and the three others drive through the mist for hours looking for help or a sign of clear until the SUV runs out of gas. On the ride they first stop at David's house where he sees his wife's dead body in a spiders web. On the main roads they see tons of cars that have been overturned, a school bus full of webbed children, and tons of debris and roadside damage. While driving, they also encounter the largest creature in the film, a massive six legged monster covered in thousands of smaller creatures and tentacles that is the size of several large buildings, and is so high that only its legs can be seen as its head is well above the trees. With the SUV out of gas they pull over. They have not been able to drive out of the mist. With Billy asleep, David pulls out the gun and nods with silent agreement with the other members of the group. David says that there are only four bullets, not enough to kill all of them, and David will stay alive and let the creatures kill him saying that he will figure something out.
Four gunshots are heard and four flashes of light are emitted from the car. David exits the car screaming for the monsters to come get him. He has shot and killed his eight-year-old son, and the three other survivors, and is now waiting for his own death. A large rumbling noise emerges in the distance, something is approaching David. Screaming and begging to die, a monster does not reveal itself in the mist. Instead it is a U.S. military tank. In fact, it is a full military battalion. Tanks, soldiers with flame throwers and rifles, and truckloads of survivors are now traveling on the road. Some of the survivors are from the grocery store and one of them is the one woman who left by herself, who is completely unscathed and has her two children with her. Realizing that he just murdered his son and three innocent people only moments before they would have been rescued and that they should have never left the market in the first place, David collapses and two soldiers approach him unaware of what David has just done.
Credits then roll.