The people of Chester's Mill panicked state when a meningitis outbreak hits the community, threatening the already scarce supply of drugs. Meanwhile, Julia continues to seek answers to her husband's disappearance

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.

As Barbie descends further into the mysterious tunnel in hope of finding Sam, he comes across a world filled with unanswered questions.

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.

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.

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.