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.

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.

Barbie and Big Jim realize their lives are more intertwined than they knew when a mysterious woman makes an appearance in Chester's Mill.

While the manhunt for Barbie continues, Big Jim gets the residents of Chester’s Mill riled up and the town demands justice for all of Barbie’s supposed crimes. Meanwhile, Joe and Norrie must find a new hiding place for the mini dome.