Spooks

During a period of intensely tight security a vital diplomatic agreement between Britain and Iran is signed,Adam and Zaf target a UK-bound terrorist with a train bomb in Tehran.

The highly-contagious plague-like virus unleashed by the Tehran blast is on the streets of London and a wounded, infected Zaf has been captured, possibly already killed.

As the team fear reprisals on Iran following the revelation of their bio-weapons programme, a UK plane is apparently hijacked and kamikazes into a US air base by terrorists.

As an Algerian extremist escapes his home-detention, the team fear he may be plotting a terror attack on US businesses in the UK with the help of local Iranians.

Attempting to stop an Iranian nuclear deal on British soil, Adam is framed for the killing of a mugger, who turns out to be a journalist investigating the Tehran train bomb.

Despite the efforts of MI5 and the CIA, the team discover that Iran has acquired nuclear triggers. Adam feels guilty for having been duped by his lover Ana, and Ros knows her alliance with the shadowy anti-American cabal Yalta have enabled Iran.

Knowing there is every chance Iran has gone nuclear, Harry and the CIA's Bob Hogan work up a plan to see off any military repercussions. The stage is set for a televised debate on a new peace deal between the US and Iran.

As the team discover the size and reach of the Yalta organisation, Ros desperately attempts to escape identification. However her betrayal is revealed by Ben Kaplan.

Having been humbled by Yalta's attack on their satellite network, the US is planning air-strikes on Iranian nuclear facilities.

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.