At the start of the film, David is sitting in his studio painting a poster. Suddenly the light goes off and there is a very strong storm. In the morning, David with his wife Steph looks outside his house, and several trees have fallen. A tree falls on top of his studio, destroying it. His 8-year-old son Billy arrives and tells him to come and see that the boathouse is destroyed. As they both go, a tree falls on the boat house, causing it to be destroyed. This tree belongs to his neighbor Brent. He goes to talk to Brent about insurance. He reaches his house and sees that a tree has fallen on his car. Burnt’s home was also destroyed due to the storm. David looking at his car didn’t talk about insurance. David is heading towards the market with his son Billy. Brent ask for a ride and he also joined the. On the way, they see many military vehicles speeding toward the mountain. They reach the market. Billy and Brent go to the market while David goes to the phone booth to call Steph, but the phone isn’t working. He also goes into the store. The store is very busy because almost everyone’s homes were destroyed by the storm. In the store, Billy and David continue to buy essentials. They are standing in line waiting for the bill when 3 military officers, Jessup Morales, and Donaldson, arrive. Cashier Sally smiles at Jessup. All three of them go around the store to buy things. Miss Reppler, a school teacher, is also there. She asks David about the storm damage to his house. Billy tells Miss Reppler about the boathouse.
A military police officer arrives and tells Jessup and the others that their leave has been suspended due to the havoc and informed them to report back. Suddenly many police vehicles pass by. The alarm started to ring and everyone is in a panic looking toward the police vehicles. Suddenly, Everyone notices a man running towards the store. He is Dan, He comes running from the other side of the road covered in blood. He enters the store and says that there is something in the mist that has killed John Lee. Suddenly, the entire city is engulfed in mist. Nothing is visible. Just mist everywhere. People trapped in the store think it is a chemical explosion. Suddenly the store starts to shake. Mrs. Carmody who is a religious lady and thinks that God uses her to speak to people says it’s death and their time has come. A woman says she has to go home, her children are at home and they will be worried. She asks everyone to support her but no one agrees. She walks out of the store alone. She disappears from view in the mist. Billy is fearing and starts crying in worry. Mrs. Reppler starts talking to everyone sitting there. David comes to the backside himself, leaving Billy with Mrs. Reppler. The generator was choking due to continuous running. He turns off the generator. In the dark, his head hits the door and he falls. He was coming back into the store by the light of the mobile when the backside shutter started banging loudly. He immediately comes to the store from there. Ollie, Myron, and Jim are coming to the backside. They stop seeing David running from there in a hurry. David asks them if they heard that voice, but Jim and Myron make fun of him. They all come back side Norm also comes with them. They try to turn on the generator but its pipe gets blocked. Jim tells him to lose it, but David refuses. Due to this David and Jim have a bitter argument. Finally, they turn on the generator and open the shutter to clear the pipe. Norm is near the shutters. Suddenly, tentacles emerge from the mist and grab him. They pull him to the outside but David jumps in and grabs him. Tentacles hit Norm. David and Ollie try hard but the tentacles drag Norm outside in the mist. Ollie attacks his remaining tentacle and it is cut and left there.
David is angry at Jim for Norm’s death. He slaps Jim. David comes back to the store and immediately changes his clothes so that his son won’t be scared by the blood on his clothes. The four of them discuss among themselves that whatever they have to do, they have to hurry because the storefront is made of all glass. They think they should tell everyone in the store. David goes to Brent and tells him everything. Brent is a district attorney in New York. David brings him to the backside and the rest confirm his words. Brent hears all of this and thinks it’s a joke instead of believing what David is saying. They offered to visit the back side and see the tentacles himself but he refused. He feels that they are trying to make fun of him because he filed a case against the store and now they want to humiliate him further. Brent and David get into a fight over this, causing everyone to rally around them. David tells everyone about the tentacles. The bug also starts laughing after hearing this. David asks Bug to go and confirm. Bug, David, and some others come to the backside. Seeing the tentacle scares the bug. One of them shakes it with a stick. The tentacle suddenly moves and a liquid comes out of it, which destroys the tentacle. Bug goes out and tells everyone about the reality. Now they all start adding bags in front of the store to cover all the glass. Mrs. Carmody is crying and praying to God in the washroom. A woman comes to use the washroom and sees her crying and sympathizes with her. But Carmody mocks her and leaves. Carmody comes out and starts a speech telling everyone that this is the end of them and it has to be done. She recites the chapter of Revelation from the Bible to everyone. She tells everyone that now is the time for them to meet the creator of this world. She is speaking when Amanda slaps her on the face and tells her to shut up. David encourages and loves his son. A man in the store asks Bugs if he has a gun, but there is no gun at that time. One of them tells them that he has a gun but the gun is in the car. Amanda has a gun that she uses for her safety. She gives the gun to Ollie as Ollie knows how to fire. Brent and some others try to leave the store as they do not believe in David. David tells him to tie a rope and leave the store so they can figure out where the danger is, but he refuses. A man in the store says he will do that. He will tie a rope and go out to the car and will take out the gun from the car. They all get out. David continues to loosen the rope. They all disappear into the mist. Suddenly everyone hears their screams and the rope is pulled with force. David Ollie holds the rope with great difficulty. Then the rope loosens and they start pulling. Blood starts coming on the rope. Suddenly, only the legs of the man appear. Everyone is very scared. They start preparing for the night. They prepare batteries, torches, and fires for the night. Sally and Jessup see each other and kiss each other. At night, everyone is sitting in front of the mirror when suddenly a huge bug crawls on the mirror. Everyone is surprised to see the bug. It is very big in size. Suddenly their number starts increasing. After a while, many huge bugs are crawling on the glass. Suddenly, a huge and strange beast-like creature comes crashing down on the glass and eats the bug. The Beast hits the glass so hard that the glass starts to crack. Suddenly, many creatures hit the glass and the glass shatters. The bugs start coming in and the creatures behind them. A bug bites Sally, causing the poison to spread through her body, and the place where the bug bit swells and Sally dies. The creature attacks the people inside and starts eating them with its bloody beak. David immediately sets fire to the sticks by tying them with cloth and starts killing the creatures. Ollie starts firing a gun at the creatures. Joe tries to set the fire but he slips and catches fire. A bug sits on Carmody’s chest but says nothing to her and flies away. A creature is walking toward Billy. Ollie comes from the other side and aims at the creature. At that point, David arrives and takes Billy aside Meanwhile Ollie shoots the creature. After a few moments, everything stops. Everyone breathed a sigh of relief for some time in this moment of pain and suffering. David also sleeps for a while but he wakes up due o Carmody’s voice. Carmody is giving a speech. David gets up and goes to the other side to visit Joe. Joe’s body has been badly burned. He consults with Ollie and the others that they should do something to get out of there and take medicine from the nearby pharmacy and help Joe and the others injured. They are all talking when Amanda arrives and tells them about Hattie’s death. She was dead next to her but she thought she might be sleeping. David picks up Hattie’s body and puts her body on the backside. David tells Amanda that they are planning to go to the pharmacy. Amanda is not allowing them to go outside because everyone who went outside in the mist is killed.
David says they are running out of medicine, their gun is running out of bullets and now they have to find a solution. David explains to his son Billy that he loves him and asks Amanda to take care of him as long as she can. They gather everyone together and talk about their plan. Carmody stands in their way. She says that because of their action, God will be angrier and will punish them more. She is yelling at them as Mrs. Reppler hits her with a tin can and tells her to stop bullshitting. Jessup also joins them. Mrs. Reppler remembers that Jim was her student and she walks along with Jim to the pharmacy. They all leave the store. They enter the adjacent pharmacy. Silence and mist everywhere. They go inside and pick up the things they need. Suddenly they hear a sound and they start hurrying. Jim’s eyes suddenly fall on the wall. He sees people clinging to the wall with spider webs. He shouts and suddenly a man grabs him. He shouts louder. David also comes there. It is the same military officer. Suddenly his stomach started to explode. His last words are that “we should not have done this”. His stomach burst and spiders crawled out from inside. Spiders attacked them. Spiders are also huge. They kept fighting and saving lives. Few of them manage to get out and reach the drugstore. They were extremely scared. Carmody was lecturing everyone. She felt that God came into her body and spoke to everyone through her. David worries as Carmody’s support continues to grow. He asks Jessup about the military officer’s last words. He says he doesn’t know anything, but his friends might. They would start looking for them. Both of them hanged themselves on the backside. Seeing this, David asks Jessup sternly. Carmody’s supporter is also standing there. He has heard all this and told to the people outside that this all is because of the military and Jessup knows about it. Everyone surrounds Jessup. Jessup says that all he knew was that the scientists were opening a window to the other dimensions of the world. On hearing this, Carmody orders to kill Jessup. The mob was already in her control. Everyone starts beating Jessup and throwing him out the door of the store. David tries to intervene but the mob stops him. Jessup kept knocking at the door but no one helped him and no one was allowed to help him. A creature from the mist picks him up.
Everyone is asleep. David is talking to Billy and they both sleep for some time. Amanda quietly wakes him up and says that the morning time is near. Ollie, and Reppler all rise quietly. They were leaving the store. Ollie tells them about the racks in which the necessary items were placed. David tells everyone about the location of his car. They slowly start leaving there. As they reach the main door, Carmody is sitting in front of them blocking the door. David tells her that they are leaving but she replies that she does not allow it. By her voice, the rest of the people also gather there. Carmody says that these are people who do not believe in God and do not follow His commandments. It is because of these people that God’s wrath has fallen upon us. These people make fun of our religion, our books, and even God. Now a human sacrifice should be made by these people so that God’s wrath can be reduced. She tells everyone to sacrifice Billy. Everyone tries to take Billy from them. David, Amanda, Ollie, and Reppler started to protect Billy. A fight would start between them. Suddenly there is a gunshot and in front of everyone, Ollie aims at Carmody and shoots her down. Everyone is quiet. They all leave immediately and run to David’s car. Due to the intense mist some of them did not reaches the car and are killed by the monster in the mist. Only David Amanda Reppler and Dan approach the vehicle. David goes home first to see his wife, but outside the house, she is also hanging dead in a spider’s web. Now they had no way and destination. They kept going as long as they had gas. There was destruction everywhere in the city. They keep going in the city. After some time the gas of the car is finished and the car stops. Now they had no choice. They look at each other but have no idea or choice left. They had 4 bullets left. In the end, everyone understood their decision. One by one they shot themselves. Only David is alive now. Fearing death, he tries but cannot shoot himself. He got out of the car and started driving. It was as if he was summoning a creature. Suddenly the mist began to subside. Army is taking control. The soldiers are on the streets. Soldiers approached to David. Seeing all this, he sat on the ground and started crying uncontrollably and started shouting.