The townspeople gather at the Dome when they realize that it survived the military attack. Big Jim orders everyone back, while Carolyn and Alice arrive to find Norrie. Linda drives up and asks Big Jim where his son is at because they need him as deputy. Big Jim says that he doesn't know and Linda tells him that Carter found Lester's corpse near the Dome. When the townspeople start to panic about the food and water, Big Jim tries to calm them down without success. While Carolyn and Alice find Norrie and take her and Joe with them, Julia asks Barbie what they're going to do now.
Linda tries to contact her deputies by radio but discovers that something is jamming the signal. She asks Barbie to help her as a deputy and he reluctantly agrees. However, he refuses to take a badge. Julia tells them that she's heading to the radio station and assures Barbie that she'll see him later. As she drives off, Big Jim tells the crowd that no one is going to starve.
At the McAlister home, Angie looks out the window at the Dome, still intact after the bombing. Junior tells her that as deputy he'll take care of her, but she grabs the snow globe he gave her as a gift, slams it into his head, and runs out of the house.
As they drive back to Joe's house, Alice tells Carolyn that she's feeling faint from the heat. Carolyn pulls over and Alice wanders into the street. When a truck comes driving toward them, Norrie shoves her mother out of the way and the truck swerves to avoid hitting them. It slams into the base of the nearby water tower and water spills out everywhere. While they get the injured driver out, Linda and Barbie pull up. Barbie realizes the danger and tells Linda that they need to head to the town's lake and start hauling water. Meanwhile, Alice tells Carolyn and Norrie that she's out of insulin, and Norrie tells Joe that her mother is a diabetic.
At the radio station, Phil discovers that his broadcast equipment is jammed by the same noise that Linda heard. Julia arrives and tells him that Linda is having the same problem, and Dodee brings in some portable tracking equipment. She hopes to find the source of the jamming via transmission, hoping that whatever is generating it is also responsible for the Dome.
After parking, Barbie and Linda walk to the lake. Linda is well aware that something is going on between Barbie and Julie, and says that she's been together with Rusty for three years. At the lake, they discover that hundreds of fish have died and floated to the surface.
At the clinic, Nurse Adams tells Carolyn that Lester destroyed the last of the insulin, endangering Alice and the other 23 diabetics in Chester's Mill. The only advice Adams has is for Carolyn to pray.
Barbie and Linda go to the town hall and tell Big Jim that the Dome cut into an underground pocket of methane, polluting the lake. Big Jim briefly wonders if it can rain inside of the Dome, but then shows them a map of the area. There are a number of artesian wells scattered across Chester's Mill, and the biggest active one belongs to Ollie Densmore. Big Jim warns them that Ollie can be difficult so he'll go out alone to talk to him.
When he's unable to find Angie in the woods, Junior goes to town hall just as Big Jim is leaving. He tells his father what happened and complains that Big Jim is the one that let Angie go. Big Jim tells him to deal with it himself and leaves.
As Barbie and Linda return to the town square, Linda explains that Big Jim and Ollie have a long history of arguing and then making up. A crowd is breaking into one of the grocery stores and they go over as the owner, Terry, tells the customers that he'll only accept batteries or propane in payment. When Linda asks what is going on, Terry tells her that money won't feed his family. The townspeople have heard about the polluted lake and are starting to panic, and Linda tries to calm them down. She finally locates someone with batteries and gives them to Terry as payment. As the crowd disperses, Linda offers Barbie a gun, but he says that it isn't a good idea to have one if they're dealing with scared people.
When Big Jim arrives at Ollie's farm, he tells the farmer that they need his artesian well. Disgusted at what he considers his poor treatment at Big Jim's hands, Ollie insists that Big Jim will have to pay him. Big Jim offers him propane to run his irrigation system and Ollie notes that Big Jim always seems to have what the town needs when it needs it. However, he agrees to make the exchange and Big Jim drives off.
Junior continues driving along the woods, trying to spot Angie. Once he goes by, she runs into town.
Carter notifies Linda that they have trouble at a food mart. When Barbie and Linda get there, Junior pulls up and Linda tells him to focus on the job at the hand. Inside, the manager is trying to ration supplies. Two customers, Clint and Waylon Dundee, are grabbing everything they can. When Junior objects, they sneer at him and call him Big Jim's little boy.
At the clinic, Norrie asks Joe to help her check the hospital files to get the addresses of the other 23 diabetics and go with her to take their insulin. When Joe wonders what she'll due to get the medicine, Norrie tells her that she'll do it no matter what it takes.
Julia drives through Chester's Mill while Dodee tracks the signal. Much to her surprise, she discovers that the signal is moving.
Angie gets to the food mart but before she can find Linda, Junior spots her. As he tries to push his way out through the crowd, Angie runs to Rose's diner. She tells a shocked Rose about what Junior and Big Jim did to her, and Rose finally accepts her story and promises to help her convince the townspeople.
Once they check the files, Joe and Norrie go to the home of Ray Garcia. As they break in through the back door, Ray comes out with a shotgun. When Norrie tells him that they're there to get his insulin, Ray says that he took the last dose a day ago and orders them off his property.
A riot breaks out at the food mart and Linda, Barbie, and the other deputies try to control it without success. One man runs off after hitting Barbie, and he runs after the man. When he catches up to him in an alley, he beats the man and then slams him against the wall and starts choking him. Linda and Carter run up and Linda tells him to back off. Barbie lets the man go and assures Linda that he won't lose control again.
Clint and Waylon break into the diner looking for Rose's food supplies. She grabs a bat and tries to fend them off, but Waylon backs her into the kitchen and grabs the bat away from her and swings. Meanwhile, Clint tries to wrestle Angie to the grown but she breaks free and jumps on Waylon's back. Waylon drops onto his back, knocking Angie out.
As the townspeople continue to riot, Linda brings out some tear gas that Duke bought ten years ago. Barbie tosses it into the crowd but the gas has lost its potency and it has no effect.
Dodee and Julia continue following the jamming signal to its source.
Norrie and Joe go to the Fannon house and discover that the door is unlocked. They search the house and find insulin in the refrigerator. However, a young boy, Scotty, comes down the stairs and asks what they're doing there. He explains that his mother went to the store and his father is outside of the Dome. Norrie assures him that they won't hurt her and Scotty, reassured, says that he's not afraid because his mother showed him how to administer his own shots. Norrie realizes that they're taking Scotty's insulin and has Joe return all of the vials except one. Scotty's mother Kay comes in and orders them out, and Norrie apologizes to Scotty as they go. Outside, Norrie admits that her idea was stupid. Julia pulls up and Dodee tells them that the two teenagers are the source of the jamming signal.
Big Jim takes three large tanks of propane to Ollie, who says that they'll make a good first payment. He warns Big Jim that if he comes back with anything except propane, he'll shoot to kill. Big Jim warns his friend that he doesn't want to stand alone, but Ollie isn't impressed.
Clint and Waylon raid Rose's meat locker and Waylon tells his younger brother to stand guard outside. Once Clint goes outside, Waylon walks over to the unconscious Angie, unbuttoning his pants.
Julia and Dodee tell the teenagers that they're the source of the signal. Joe reluctantly tells them about their seizures and show them the video they took at the clinic.
As Barbie tries to stop the rioters, he sees Clint standing suspiciously outside of Rose's diner. He goes over and Clint runs, and Barbie goes inside. When he sees Waylon preparing to rape Angie, Barbie jumps him, applying a choke hold until he passes out. Barbie then carries the unconscious Angie outside as Linda comes over. Once he tells Linda that Rose is dead, he takes her car keys and prepares to drive Angie to the clinic. They discover that someone has slashed the tires and the rioters are getting close. Linda reluctantly draws her gun and prepares to shoot... and it starts raining. Big Jim pulls up in his truck and tells the townspeople to gather all the water that they can. Barbie tells Big Jim about Rose and asks him to get Angie to the clinic. Linda recognizes the Dundee brothers from Barbie's description and Big Jim tells her to find them.
Julia drives the others to the dome boundary and Joe touches the dome. As it rains, Dodee explains that the Dome now has its own micro-environment. The evaporation process will filter the methane out of the water, purifying it. As Norrie touches the dome, she gets shocked and the car radio comes on. They realize that the jamming signal is gone, and Julia figures that it's because Norrie and Joe both touched the Dome.
Norrie and Joe walk back to the clinic to get the insulin to Alice. Julia suggests that the Dome is using the two teenagers and that it is protecting them, providing them with the water they need and protecting them from the bomb. Dodee isn't convinced and says that they need to tell Big Jim what happened. Julia warns her that the townspeople will turn on the teenagers if they think they have anything to do with the Dome, and Dodee reluctantly agrees to keep their secret.
That night at the clinic, Norris gives Carolyn the one vial of insulin. She worries that it won't last forever and Carolyn tells her that they need to focus on the fact that Alice is safe for now.
As Julia drives down the street, she sees Barbie standing in the rain and pulls over. He admits that it's been a heck of a day and Julia tells him that they'll be okay... and then kisses him.
Angie wakes up and finds herself in Big Jim's living room. He sitting there waiting for her to wake up and tells her that Rose is dead. When Angie wonders why she's there, Big Jim tells her that she's not a prisoner. However, he wants to come to an arrangement with her about keeping Junior's behavior secret. Big Jim admits that Junior has always been disturbed ever since his mother died, and promises Angie that Junior will never touch again. In return for her silence, Big Jim will protect her and make sure she has whatever she needs to survive. Angie asks him to take care of Joe as well in return for her silence, and Big Jim agrees. Junior comes in at that moment, sees Angie with his father, and demands to know what's going on.