In 1974, biologist Philip Carvel makes the acquaintance of a young well-connected woman in the British government. She's the first one to take his warnings seriously about how the planet can't sustain humanity's growing numbers, and the two of them put into action a plan that will render 95% of the world's population sterile.
The Network tortures Jessica for the nature of the adjustment that her father made to Janus. Meanwhile, Ian and Grant try to find Becky, and Arby tries to make a new life for himself but receives a visitor from his past.
Arby takes Ian, Becky, Grant, Donaldson, and Anton into hiding, and they soon work out who Anton really is. They go to a teenager hacker, Ben, who confirms what the Network has planned. Meanwhile, Lee and Wilson work together to track down the fugitives, while Michael is forced to betray a new friend to protect the Network's secrets.
Dugdale reluctantly agrees to harbor Jessica and after he visits Jen and Alice in a secret prison it's clear he will do whatever The Network asks in order to keep his family safe. Jessica is looking for Ian, as is Milner who believes that he will lead her to Carvel.
After Arby abducts Anton and Grant, Ian and Becky set out to find Michael... which leads Wilson to them. They convince him to analyze Anton's sketch and he realizes that Philip's adjustment to Janus is far worse than they anticipated. Meanwhile, the Carvel family has a reunion.
Wilson takes the group to a private Network hospital. While the doctors tend to Arby's near-mortal wound, Jessica looks after her brother while Ian, Becky, and Wilson set out to find Terrence Truman, the Network agent who plans to release the Russian flu virus. Terrence is unaware that the vaccine containing Janus won't work and that flu will wipe out millions.