COBRA is assembled when fresh disaster strikes, as a breach at Dover port suggests an insidious threat. The PM's strategy is tested by an online activist.

Following devastation in Kent and the cyber-attack which continues to jam communications, the Prime Minister convenes an emergency COBRA meeting.

With the nation in the full grip of the crisis and experiencing the worst blackout in the history of the UK, Sutherland and his team are forced to work around the clock to restore power. Meanwhile Anna reconnects with Edin, but this dalliance with her past love becomes more dangerous than she anticipates.

As the country continues to face darkness, Sutherland, Anna, Fraser and their teams pay a visit to the worst affected area in Northumberland to see the situation on the ground. But with the Prime Minister away, Archie’s incendiary comments on the dark underbelly of public mood threatens to cause more problems for everyone.

As questions are asked about Sutherland’s knowledge of his daughter’s involvement in her friend’s death, Anna seeks the help of Eleanor in handling the new revelations about Edin. Meanwhile, a new threat rears its head as public sentiment grows more turbulent.

Prime Minister Robert Sutherland, his Chief of Staff Anna Marshall and new Home Secretary Joseph Obasi assemble the emergency committee “COBRA” to respond to a potentially explosive situation in Kent.

The team try to understand the latest discovery, while Francine's attack on Lord Singer is met with delight by the Labour leader.

With the knowledge that his daughter is alive, Robert Sutherland turns his focus on handling the aftermath of the sinkhole collapse and dealing with the abduction of Princess Yadira.

As the possibility of a solar storm affecting the UK mounts, the Prime Minister Robert Sutherland, his chief of Staff Anna Marshall, the Head of the Civil Contingencies Secretariat Fraser Walker and the Home Secretary Archie Glover-Morgan assemble the emergency committee “COBRA” in an effort to combat the situation.

As anarchy explodes on the streets and the nation is rocked with night upon night of rioting, Fraser and his team reach the endgame in their mission to get the lights switched back on in the Red Zone. Meanwhile, with his personal life imploding, Sutherland is forced to fight for his political life as Archie finally fires his first shots…

With the nation sliding further and further towards anarchy, Rachel faces difficult questions about Ellie. Meanwhile, Fraser says goodbye to his father and grows closer to Francine. And as the influence of “People’s Justice” grows ever-powerful, Sutherland is forced to consider more extreme measures to retain control of the country.

Following the sinkhole collapse, Robert and Rachel hurry to the site in the hope that Ellie might still be alive. Unbeknownst to them, Ellie has made a shocking discovery underground.

The government faces intense scrutiny for legislating an anti-protest bill deemed to be too aggressive, leading to police forces deciding to go on an unofficial strike in response.

Robert and Anna return to COBRA to try and devise an effective strategy against members of an environmental protest group who are blocking traffic from going through a railway tunnel.

While the government frantically launches a search operation to recover a stolen weapon, Dan and his group of mercenaries threaten to use it unless their demand for a ransom gets met.

Rachel Sutherland is dismayed by the fresh media assault on her reputation, but Robert is distracted - for somehow, Firestorm is back, and spreading misinformation about the water supply.

Dan breaks into Archie's home, demanding that Robert resign from his post of prime minister or he will resort to using the weapon.

Reeling from the events in Kent, the COBRA team are briefed by Eleanor on the nature of a sophisticated malware which has infected the UK’s critical infrastructure.