S1, E2: As the net begins to close on Philby, he’s summoned back to London as suspicion grows that he is a Soviet spy, working within MI6. His colleague, Nicholas Elliott, defends his friend's reputation, insisting that he is innocent. For the next 12 years Philby, with Elliott's unwitting help, manages to charm and bluff his way out of every accusation. Then, in January 1963, Philby's luck runs out.