Series Finale: As the Dome in Chester's Mill comes down, the Resistance makes a final attempt to protect the outside world from the infected townspeople in the Kinship and their new queen.

A year after the dome disappears, Barbie, Joe, and the other townspeople gather for a memorial. A year earlier, Julia and Junior try to rescue Barbie and the others, but run afoul of Big Jim.

When the Dome’s calcification process accelerates, Chester’s Mill has 24 hours before the barrier’s breakdown will suffocate everyone inside. While the new deadline puts added pressure on Joe to bring the Dome down, Barbie and Julia race to save his child from The Kinship. Also, Big Jim tries to manage the increasingly volatile Hektor, who is adamant that infected townspeople never escape the Dome.

The residents of Chester’s Mill try to move on with their lives in the aftermath of their mysterious experience in the tunnels beneath town. Meanwhile, Big Jim suspects new residents Christine and Eva are keeping secrets concerning the Dome.

Under the guise of helping Chester’s Mill rebuild, Christine urges the townspeople towards specific individuals and projects that remind them of their experience in the tunnels. Also, Julia and Big Jim make shocking discoveries that reveal a new threat within the Dome.

Members of The Resistance race to release their loved ones from Christine’s influence before she reaches her end game for the Dome. While Barbie risks everything in an attempt to free Eva from the Kinship, Big Jim and Julia are enlisted by Hektor, the head of Aktaion, to test a possible cure for infected townspeople. Also, Joe chooses to work with Christine after she shares some shocking information about the entity behind the Dome.

Barbie investigates Ben's claim that something strange is going on in Chester's Mill, but Eva surprises him with unexpected news. Meanwhile, Norrie and Hunter grow closer, and Christine advises Joe to move on.

Big Jim and Julia form a tentative alliance to search for proof that will discredit Christine, which leads them to new information about the Dome’s capabilities. Meanwhile, when tensions run high in town and threaten Christine’s leadership, she puts a plan in play that has deadly consequences.

Big Jim, Julia, Joe, Norrie and Hunter join together to form a resistance against Christine, who is mobilizing residents to work on a massive excavation project in the caves underneath the town. Also, Hunter uses his tech skills to contact the outside world.

The Resistance, the citizens not under Christine’s control, join forces with an unexpected ally: Hektor Martin, the nefarious head of Aktaion. Despite Hektor revealing more about the Dome’s origins and helping to strike back at it, Big Jim and Julia still worry he will betray them. Meanwhile, Hunter receives encrypted files that give disturbing insights into the final effect the Dome will have on the infected townspeople.

When Rebecca discovers an infestation of butterfly eggs on the crops, Barbie risks his life to help her save the town's food supply.

After Big Jim and Rebecca's plan left the town divided, Julia takes over as the leader of Chester's Mill; Norrie and Joe help Melanie find more clues.

When Big Jim is captured by Aktaion, the dangerous private corporation that’s descended on Chester’s Mill to harness the Dome’s energy capabilities, he’s forced to manipulate Christine for information about her agenda. Also, when Joe and Norrie question the town’s new rules, they find themselves in a dangerous face-off with the increasingly unstable residents.

The latest threat intensifies, leaving Chester's Mill residents at risk of being crushed to death; Melanie's health declines as the egg's fate remains uncertain.

Big Jim and Julia devise plans to end Christine’s control over the town by initiating a life-or-death plot involving Barbie and Eva, while Joe and Norrie conduct research to better understand the Dome’s ultimate agenda. Meanwhile, Hunter finds more information about the true head of Aktaion, the nefarious private corporation that wants to harness the Dome’s energy.

When a former deputy goes rogue, Big Jim recruits Barbie to join the manhunt to keep the town safe. Meanwhile, Junior is determined to escape the Dome by going underground.

Big Jim conducts a census to see how long the town can survive on dwindling resources; acid rain threatens everyone.

A cave-in severs Barbie and Sam's path back to Chester's Mill during their investigation of a mysterious tunnel; a dust storm rages through the town, as Big Jim and Julia face off in a power struggle.

Rebecca and Sam try to save Chester's Mill residents as temperatures plunge; Barbie puts his life at risk to help Julia after a terrible accident.

Just as the walls start to close in on those trapped in Chester's Mill, a possible exit from the dome is revealed.

Julia uncovers the truth about her husband's disappearance and unravels some of Chester's Mill's darkest secrets. Meanwhile, Maxine shows Barbie how she plans to take control of the town.

Rebecca and Big Jim consider extreme measures as the conditions worsen in Chester's Mill; clues about Melanie's connection to the dome are revealed.

When the town begins to run low on water, the residents of Chester's Mill begin to fight for the remaining resources. Meanwhile, Julia discovers a strange connection that two of the town's residents have with the Dome.

As the world outside the Dome is rocked by a catastrophic meteor shower, unexpected alliances form inside the barrier. Eva tries to indoctrinate Barbie deeper into The Kinship and Big Jim and Julia turn to one another while isolated on Bird Island outside of town. Also, Joe is forced to accept help from Sam, the man who killed his sister.

Following Duke's death, his house catches fire, forcing the town to rally together to form a bucket brigade. Elsewhere, Junior ambushes Barbie, while Dodee and Phil pick up a military frequency.