An environmental terrorist group storm the Thames Barrier and threaten to flood London. They demand that the government publish a secret document entitled 'Aftermath'.
The Deputy PM denies any knowledge of the document, making it impossible to meet the terrorists' demands.
The team suspect that the Deputy PM is hiding something. They discover that the Aftermath document does exist and it's political dynamite. It's a proposal to abandon any attempt to tackle global warming and instead build on economic and military strength so that Britain and America can control the remaining resources.
Meanwhile, Adam enters the Thames Barrier in an attempt distract the terrorists so that Special Forces can storm in. But during the negotiation another post-traumatic stress attack seizes him. Ros agrees to take Adam's place in the proceedings, but the terrorists increase their demands.
With the threat of a catastrophic tidal wave engulfing London, Harry gives orders to blow up and flood part of the Thames Barrier. Unfortunately it means possibly killing Ros and Adam.
The blast goes off and Ros and Adam try to escape but find themselves trapped. Just as they run out of air, Adam manages to break through a vent in the roof and the exhausted pair burst through the surface of the Thames.