With the clock ticking on how long the Family can remain in the dangerous city, Tom leads a desperate attempt to find Abby. With Abby still missing and Greg recovering from his injuries, the Family are left scavenging for survival in the city. While Naj leaves graffiti messages for Abby, Tom steals supplies from other survivors. The Family learn that more people have been abducted like Abby, and that the kidnappers bear the markings of a known pharmaceutical company. As Tom leads Al, Anya and Sarah off on this trail, Greg and Naj find themselves confronted by the group Tom stole from. In the Lab itself, Abby is re-infected by Whitaker, who will stop at nothing to find his miracle vaccine...