Beth goes undercover for the first time for MI-5.
An FSB Officer is welcomed onto the Grid to help track down a rogue nationalist from Azakstan.
A trio of Chinese agents arrive in London and the team must find out why.
The relationship between the CIA and MI-5 are put to the test when things go wrong in Afghanistan.
Beth and Dimitri go undercover as Home Office representatives, in order to protect the American president who is in London for top-secret peace talks.