After Yurchenko's shocking disclosure, the CIA and FBI mobilize to bring the brilliant Edward Lee Howard to justice. Despite Howard being fingered as the mole, Sandy remains concerned about potential agency leaks and works tirelessly to prove that her asset, General Polyakov, is attempting to establish contact with the CIA.

Cast: Jodie Whittaker, Paul Rhys, Harriet Walter, Ralph Brown, Stuart Milligan, Christina Cole, Catalina Denis, Julian Ovenden, Lex Shrapnel, John Lynch, Noel Clarke, Goran Kostic, Jonjo O'Neill, Akie Kotabe, Elen Rhys