The residents of Chester's Mill appear both inside and outside the dome following their mysterious encounter in the tunnels beneath the town.

The townspeople are forced to question who they can trust when new residents emerge.

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.

When Big Jim and Julia team up to find proof to discredit Christine, they learn something new about the dome. Meanwhile, when Christine's leadership is threatened, she puts a plan into motion with deadly consequences.

After being captured by Aktaion, Big Jim is forced to manipulate Christine for information about her agenda. Meanwhile, when Joe and Norrie question the town's new rules, they find themselves in a dangerous face-off with the increasingly unstable residents.

As the outside world is rocked by a catastrophic meteor shower, unexpected alliances form under the dome. Meanwhile, Eva tries to indoctrinate Barbie deeper into The Kinship.

A resistance forms against Christine, who is organizing a massive excavation project in the caves. Hunter and Big Jim make contact with the outside world.

Julia and Big Jim come up with a life-or-death plan involving Eva and Barbie intended to end Christine's control over Chester's Mill. Hunter investigates Aktaion.

An unlikely alliance is formed; Hunter receives files that reveal disturbing details about the infected townspeople.

As the dome's calcification accelerates, the townspeople have 24 hours left before they will suffocate; Julia and Barbie race to save Barbie's child; Hektor is adamant that the infected townspeople should never escape from the dome.

As the dome comes down, a final attempt is made to keep infected townspeople from impacting the outside world.