After Sparks attempts to quarantine Molly, she and her family seek refuge on a remote island with her estranged father, Quinn. When the agency closes in on their whereabouts, Ethan is exposed to grave danger. Meanwhile, Yasumoto experiments with a strange and deadly substance.

John begins to doubt Molly's mental state when the validity of her pregnancy is questioned. Meanwhile, Ethan suffers a serious setback, and John and Julie disagree over how to care for him.

When Molly finally comes face-to-face with her offspring, she realizes she may be the only one who can stop the coming danger. Meanwhile, Julie uncovers grave secrets about Odin.

As Molly succumbs to the virus, long forgotten memories surface. Also, Julie is confronted with hard choices and the Hybrids seek revenge.