Spooks - Series 6 (2007)

Adam and Ros recover to find London facing an even greater threat. While attempting to thwart an attack that could jeopardise a historic peace accord between Britain and Iran, the team unwittingly unleash a deadly killer. But with a virus that mimics the pneumonic plague, there can be no negotiation. And when Zaf is kidnapped by armed mercenaries, the team realises that in a game of the highest stakes they hold none of the cards. As the stuff of nightmares becomes increasingly real, London faces total devastation.