In the second-season premiere, Drs. Peter Farragut and Sarah Jordan are joined by Kyle Sommer when they battle a new deadly virus on a mysterious wooded island.

The CDC team continue to investigate the island; at the same time, they discover Peter's brother, Alan, is a member of Brother Michael's cult, and his warnings for them to leave the abbey fall on deaf ears.

Jordan and Peter travel outside the safety of the abbey to retrieve some specimens and discover just what's living in the woods; at the same time, Sister Amy plots to make the CDC team leave forever.