Just as the British launch a peace process meant to stabilize its relations with Iran, MI-5 learn that a rogue Iranian intelligence officer, Megan Asnik , may be plotting an attack. Zaf and Adam go undercover in Tehran with the intent to assassinate Aznik before he can cause any real damage. Their attempt to get him fails but results in the death of many innocent Iranian civilians. When Aznik shows up in the British Embassy requesting asylum, he claims to be a double agent who has been feeding the West information about Iran's biological weapons development. His handler is code-named Copenhagen. Realizing they've been set-up, MI-5 needs to identify Copenhagen and find out exactly what is going on. Written by garykmcd

With the virus spreading, Harry Pearce decides to take extraordinary action to find out who might have an antidote. They determine that one of four countries likely has it and he decides to kidnap and if necessary torture the station heads for India, Russia, France and the United States to get the serum. Harry turns to a former colleague for assistance in extracting the information. Zaf and Adam meanwhile have both been infected and the clock is ticking. Adam is released but Zaf is kept prisoner by the unknown assailants working for 'Copenhagen'. Written by garykmcd

The crash of a cargo airplane near a secret US army base diverts MI-5's attention from the Iran situation. The Ministry of Defense has put out press releases saying it was equipment malfunction but MI-5 learns they may have been carrying biological weapons on board. The US base is known as the UK's own Area 51 and there is a permanent camp of UFOlogists convinced that there is some connection with alien life. Malcolm goes undercover to find out what is really going on. It all comes full circle when the crash is found to be related to the Iran situation and the identity of Copenhagen is revealed. Ros meanwhile goes off on her own - and against specific orders - to find Zaf who she is convinced is still alive. She is kidnapped by a group known as Yalta, a pro-British/anti-American group that is trying to recruit her. Written by garykmcd

Abdul Kharami is a suspected terrorist who is under constant surveillance but manages to evade his watchers just as MI-5 receives reliable information that he may be ready to stage an attack. Kharami specializes US targets and given the Americans set them up with the Tehran explosion, Ros for one thinks they should just ignore him. Harry Pearce thinks otherwise and brings his American counterpart, Bob Hogan, up to date. He also authorizes the launch of Operation Zebra, MI-5's plan to infiltrate the CIA. When Kharami's plan is traced to the Iranian Special Consul, Adam uses his special contact there to find out what is going on but it goes horribly wrong. As Ros learns from her Yalta contacts, Kharami's intentions - and his target - aren't are as straightforward as MI-5 may have thought. Written by garykmcd

MI-5 has Sergei Valentino, a freelance Russian, under observation from the moment he enters Britain. He has in his possession blueprints for a nuclear trigger which they believe are destined for the Iranians who seem bent on developing a nuclear weapon. Soon after his arrival they lose him however and Ros uses her Yalta connections to find out where he is. Yalta expects something in return, however. Adam meanwhile has his own problems after he accidentally kills a mugger who turns out to be a journalist who was investigating the Tehran bombing. Adam has been hiding Ana Bakshi in an MI-5 safe house without permission and Harry Pierce thinks she might be leaking information. He's definitely been set up, but the source lies elsewhere. Written by garykmcd

Adam and Ros board an airplane to identify a courier carrying nuclear weapons technology to Iran. Jo and Malcolm race to prevent the poisoning of London's water supply which Iran has threatened if the courier does not reach his destination. Written by Anonymous

Knowing that Iran now has the nuclear triggers to complete their armament program, Harry Pearce convinces his CIA counterpart Bob Hogan that the time has come to seriously negotiate with the Iranians. Their proposal to Iranian envoy Dariuch Bakhshi is that in return for Iran remaining silent about its nuclear capability, the US and Britain will regularize relations with them and sign a trade agreement. Bahkshi clearly wants more than they are offering but Harry has an ace in the hole - safe passage and a new identity for his wife Ana, whom Bahkshi learns is still alive. They agree to go on television that evening to make the announcement but the live broadcast is hijacked by right-wing extremist out to expose the secret deal that the government has made. A former intelligence officer now under arrest tells them about Yalta and that there is a mole deep in the intelligence service. Written by garykmcd

Ros's relationship with Yalta is revealed. With limited options, she turns herself in, but convinces Harry that his best option is to send her back out as a double agent.

After Yalta's attack on their satellite network, America is planning air-strikes on Iranian nuclear facilities. Harry's team are suspended from the Grid following the Ros Myers affair, and, when utterly impotent and isolated, an old adversary of Harry's appears out of the woodwork to inform them of a bomb he's planted in London. Written by Anonymous

War with Iran finally averted, the team learn that a London school will be the target of hardliners resisting the new peace. Simultaneously they discover that their lost colleague, Zaf, was grotesquely tortured and killed by a group of mercenaries. When Jo is snatched by the group, Adam resists calls to stay focused on the school threat; the war has become personal and he must find Jo at all costs. Written by Anonymous