A mysterious hacker group, The 404, initiates a devastating ransomware attack on a Norwegian gas installation. The hack, a coordinated phishing and social engineering operation, makes the news. A high profile attack like this quickly gains the attention of AJ, Mark and Maurice, aka ‘Good Shepherd Cybersecurity’.

Good Shepherd Cybersecurity is invited to deal with the energy company’s ransomware attack. Mark advises the CEO not to pay the ransom at any cost. It’s not clear if he’ll take Mark’s advice. George, Mark and Violet’s estranged father, makes an unexpected appearance. There are clearly serious questions to be answered.

Disastrously, despite all advice, the energy company’s CEO is planning to cave in to the ransom demand. Mark buys time, promising his team will extinguish the threat in days. Maurice is as elusive as ever. However, the arrival of a Europol agent on the scene brings some nervous moments for both him and Mark.

AJ informs the team that a fake calendar request to the initial phish victim enabled the hackers to access vital engineering systems. George tries to explain his motives to Violet, but she isn’t convinced. Mark in the UG & E war room thinks he has worked out the nuts and bolts of the hack. He sends in Lars in Norway to rectify the situation, but there is a terrifying reaction.

Mark has enlisted Lars to locate the threat in the plant’s underground system of tunnels and comes to a stunning realization about the real nature of the attack. Thanks to a USB key, AJ manages to persuade a sceptical CEO that security training needs to happen. Meanwhile, Fiona sees something that triggers her own doubts about Violet when she runs an errand at Mark’s home.

Mark and AJ have an exciting ride out to inspect one of the stricken gas terminals, thanks to an old friend. In the offices, the GSC team watches nervously as Mark heads out into the deserted control room. The monitoring systems at the facility are going critical. Charlotte’s reaction when Lars and Mark are successful is beyond anything witnessed before.

Maurice enlists Deathrage to do a little cyber-snooping on Agent Castillon to see where her loyalties lie. AJ’s growing social media presence secures an approach from a hugely popular influencer whose social media feeds have been hacked and damaging deepfake messages have been posted. Maurice reveals his old life is very much alive alongside the Zen guru persona.

Violet has a flashback to the moment when 16-year-old her was finally able to cut loose from George. Back in the present day, George tries to persuade Violet to get some old tech off Mark allegedly to protect him. Later, Violet is instrumental in putting together the response to deal with Rosie May’s social media crisis: an ingenious deepfake.

Violet and AJ have worked out the scarily simple mechanism behind the hack of Rosie May’s social media feed. The influencer is delighted, and everyone at GSC is in a celebratory mood. Mark and Violet seem to have worked past their differences and are bonding over an old gaming console. Never short on surprises, Maurice brings an unexpected guest to the party.

Fiona still has her suspicions about Mark’s sister and is intrigued to see Violet visiting a surprising location. Over at Good Shepherd Cybersecurity, a normal day is quickly taking an unexpected turn. How will Mark and the team respond in the face of this new, unforeseen crisis?

All is descending into chaos. The Good Shepherd Cybersecurity team is driven out of their office. Erica makes a devastating discovery about Maurice, while Mark receives more humiliation from the mastermind behind the 404. Everyone thinks he’s a hero, but he knows the awful truth and the enormous personal price he has paid.

The morning after the attack, the team is trying to process what happened. A search through the security camera footage turns up some nasty surprises. Mark is shocked at what he sees and goes to confront the culprit; he feels betrayed and lied to. What seems like an ending is just another beginning. He wants to be master of his own destiny and take on his enemy, no matter what the consequence.