As the war winds down, civil servant Feef Symonds is recruited by American intelligence agents to identify Russian spies in the British government.
In Peter's absence, Rowe steps in as Feef's handler while she attempts to infiltrate the Cabinet Office; Hugh confronts some realities of politics.
Rowe pushes Feef toward riskier tactics as Garrick grows suspicious of her; the latter days of the late Phillip Jarvis are detailed more deeply.
As Feef develops reservations about work, Hugh becomes mired in the debate over the Middle East; Rowe believes he has found a Russian mole.
Feef searches for information on Peter while Jackson seeks some answers of his own; Rowe makes an impassioned pitch for expanded operations.
A contentious meeting with one of Rowe's colleagues pushes Feef and Jackson to look for a way out; tensions between Garrick and Feed come to a head.