An Iranian arms courier in London has procured a circuit board that will finally enable Iran’s nuclear warheads and, in order to prevent the boards reaching Tehran, Harry (Peter Firth) orders all planes grounded, as the contemporary spy drama continues.
But with Ros’s (Hermione Norris) bugs in place on the Grid, word of this plan leaks fast and MI5 receives a threat that a lethal chemical will be released into London’s water supply unless the courier is able to reach Tehran. Harry orders a security sweep on the Grid as Ros desperately attempts to dispose of the bugs.
Armed with further intelligence that the courier is British, the team manage to establish which plane he is on and Adam (Rupert Penry-Jones) and Ros both board undercover � Adam as a passenger and Ros as an air stewardess.
Meanwhile, Jo (Miranda Raison) and Malcolm (Hugh Simon) find the source of the poisoned water supply and must find a way to prevent the release of the chemical, without the terrorists learning that their threat has been foiled.
As the plane draws nearer to Iranian airspace, tension mounts � Adam and Ros must identify the courier from the passenger list, or ground the plane before it enters Iran.
Adam accidentally kills a man he is convinced must be the courier, but then discovers that it is the pilot who must be the culprit. But, as the instigator of a deadly assault, no one will listen to Adam and he is apprehended. It is up to Ros to prevent the pilot escaping with the circuit boards that will give Iran instant nuclear capability…
Tuesday 20 November 9.00-10.00pm BBC ONE