The inhabitants of a town in Maine called Chester's Mill are forced to deal with a bizarre situation as they find their town enveloped by a dome-like force field.
After Duke dies, a fire in his house causes the townsfolk to come together in an effort to put it out. Meanwhile, Barbie gets stalked by Junior, and Dodee picks up a military frequency at the radio station.
Following the killing of a deputy, a manhunt is organized by Big Jim to catch the killer. Elsewhere, Joe and Norrie are still suffering from odd seizures.
As an outbreak of meningitis occurs in Chester's Mill, Julia discovers that Barbie may have information about her missing husband.
As the townsfolk's loved ones from outside the dome visit Chester's Mill, Barbie finds out that the military is planning to fire a missile at the dome to destroy it.
Julia and Dodee set out to find the cause of the radio signal jam, believing that it can help them uncover the origin of the dome. Meanwhile, chaos reigns as the townsfolk start fighting for water after the water tower gets destroyed by accident.
As Harriet, Julia's pregnant neighbor, touches the dome, she goes into premature labor. Meanwhile, Joe and Norrie stumble upon something unexpected, and Linda looks for the Dundee brothers following a horrible incident.
As Norrie mourns the death of a loved one, Julia is shown the mini-dome by Joe, while Big Jim devises a plan to stop Ollie after the latter seized the provisions.
A criminal whom Big Jim and Barbie know resurfaces. Barbie goes to see the mini-dome with Julia, only to discover it has vanished. Angie begins to get the same seizures experienced by Joe and Norrie.
Barbie and Big Jim are still being manipulated by Maxine. On the other hand, Angie discovers who the fourth hand is, and Linda and Julia look into Duke's connection to old crimes in town.
As a spell of bad weather hits Chester's Mill, Julia gets shot, while Big Jim manages to get Linda to believe that Barbie poses a huge threat and that Big Jim's stash of propane is protecting the town.
As Big Jim frames Barbie for crimes he did not commit, the townsfolk turn against Barbie. After the mini-dome is taken to Ben's house by Joe and Norrie, it starts behaving in a peculiar way.
As the monarch hatches, the butterfly brings about unforeseen occurrences. The townsfolk take fright when the dome turns black. Julia and Angie help Barbie break out of jail.