It has been three months since the destruction of the Utopia manuscript, and things have been quiet for Ian, Becky and co. Believing the Network to be finished, they each try to get back to some semblance of normality. But far from being over, the Network are only just beginning...
In 1974, young scientific genius Philip Carvel meets an idealistic security services agent, Milner, at a secret forum of political, industrial, financial and academic leaders. Milner is in charge of a powerful shadowy organisation known only as The Network.
In the present day, Jessica has been held captive by Milner who has tortured her in a desperate attempt to find out just what adjustment Carvel made to Janus. Ian and Grant are desperately searching for Becky. The Network is planning V Day — a strategy to vaccinate the whole world from Russian flu and Geoff is being forced to sell the idea to the nation.
The gang are on the run and find a precocious young hacker, who uncovers the key to The Network's new plan: a real global outbreak of weaponised Russian flu that will prompt the entire world to take up their vaccine on V Day.
A shocked Dugdale reluctantly agrees to harbour Jessica, but who should be scared of who? When Dugdale visits Jen and Alice in a secret prison it's clear he will do whatever The Network asks in order to keep his family alive. Jessica is searching for Ian, as is Milner who is convinced he will lead her to Carvel.
In the penultimate episode, following the revelation that her father is alive, Jessica sets off to find him, with hostage Milner in tow. Meanwhile, Wilson and Leah analyse their information and discover the far darker and more terrifying secret it holds.
In the final episode the race is on to find out who is going to release the flu. The gang track down Dobri Gorski to a police cell, where he tells them the names of the three people he trained to release the flu. A process of elimination leaves them with Terrence, but they still have to find him. Wilson's new ruthlessness is unnerving - can he be trusted? And what will happen when Becky runs out of Thoraxin?