Calum is attacked by muggers who take his laptop containing classified information on MI5's undercover agents, leading to a race against time to prevent the next spy on the list being attacked. Meanwhile, Harry meets Elena at the ballet, but Russian counter-intelligence agents are on her trail, forcing her son, Sasha, to take action to prevent his mother being revealed as a former western spy. Peter Firth, Alice Krige and Geoffrey Streatfeild star.