In 1974, genius Philip Carvel meets an idealistic security services agent, Milner, at a secret forum of political, industrial, financial and academic leaders... by 1979, Carvel's losing his mind.

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

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.

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.

Following the revelation that her father's alive, Jessica sets off to find him, with hostage Milner in tow. Wilson and Leah analyse their information and discover a far darker, more terrifying secret.

In the final episode the race is on to find out who is going to release the flu. The gang track down Dobri Gorski, where he tells them the names of the three people he trained to release the flu.