Harry has been arrested on suspicion of the death of the CIA's deputy director, but the officers of Section D break him out of custody. Elena Gavrik informs Harry of a plot to attack the UK.
Harry, convinced that deputy-director Coaver is behind recent attacks on MI5 and Ilya Gavrik , kidnaps and interrogates him, but it soon becomes clear that someone else may be behind attempts to sabotage the burgeoning relationship between the UK and Russia.
Two Islamist suicide bombers kidnap the daughter of a valuable MI5 asset. Elena is targeted for assassination, and Harry becomes increasing suspicious of the CIA's deputy-director.
Dimitri tries to get close to an anarchist suspected of plotting to use a dirty bomb. Ruth is offered a position as security advisor to the Home Secretary. Harry suspects that the Americans may be behind the compromising of MI5 assets and the attempted assassination of the Russian foreign minister.
Callum is mugged and loses a laptop containing highly classified details of undercover agents, which are soon leaked as part of a plan to discredit MI5. FSB operatives in London threaten to expose Elena's past as an MI6 asset.
A former Cold War colleague of Harry's is murdered, and it appears that the assassin may be targeting the Russian foreign minister, in London for high level talks with the UK government. The minister's wife, Elena, is a former asset and believes that Harry has asked her to resume passing on intelligence about her husband.moreless