Barbie's life is in Big Jim's hands; the dome becomes magnetized; Julia tries to save the life of a mysterious girl who may have clues about the origin of the dome.

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.

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