For those of you (like myself) who were mystified by Tuesdays episode then here is a summary of what was supposedly happening -
'Section D receives intelligence that a plane has crashed near an American airbase on UK soil, and fear that it may have been shot down on purpose. They need to find out what really happened - if Iran were involved, the reprisals could spiral into war.
With the team unaware of her kidnap, Ros is subjected to mental torture but, when released, she learns that it was all a recruitment exercise. 'Yalta' is a shadowy international group of double agents and senior government officials who work together in an attempt to thwart American dominance in world politics - they want Ros to join them.
With their offer playing on her mind, Ros returns to the Grid where she and Jo interrogate a source of Jo's from the MoD who reveals that the Americans were illegally testing their controversial new spy plane, Aurora, in UK airspace when it collided with a freight plane.
The team investigate Aurora's recent flight routes and learn that the craft also tracked MI5's recent operation in Tehran. It becomes clear that America were behind the false intelligence which led to MI5 setting off the bomb in Tehran. Knowing that the bomb would expose Iran's possession of biological weapons, the US hoped to justify military action towards them.
Learning that the US is prepared to manipulate Britain, its closest ally, is the motivation Ros needs to make her first contact with Yalta. Not for the first time, she is on the path to becoming a traitor. '