In 1960s London, Charles Dobbs is a staid
MI6 operative investigating
Foreign Office official Samuel Fennan, a former Communist who apparently commits suicide. Dobbs becomes suspicious about the cause of Fennan's death while visiting Fennan's widow the morning after his death. When a wake-up call is received at Fennan's home, his widow Elsa says the call was for her. Dobbs discovers this to be a lie and as a result suspects that Elsa, a survivor of a Nazi
extermination camp, might have some clues regarding Fennan's death. Other government officials want Dobbs to drop the case. However, Dobbs privately links up with retired police inspector Mendel to continue enquiries and they uncover a network of East European agents, one of whom assaults Dobbs, breaking his hand. Dobbs also discovers that his promiscuous wife Ann is leaving him to go to Switzerland to join a former World War II colleague, Dieter Frey. Dobbs ultimately decides to set a trap to prove that Elsa is a spy and to uncover her control by arranging a rendezvous which takes place in the Aldwych theatre during a performance of "
Edward II". Dobbs, his colleague Bill Appleby and Mendel observe Elsa and wait to see who will sit in the empty seat next to her. Dobbs is sickened to see that it is Dieter who sits down next to Elsa and is her control. When Dieter and Elsa realise they have been set up, Dieter quietly kills Elsa and slips out of the theatre. Mendel follows Dieter to his hideout and summons Dobbs. In the final confrontation, Dieter shoots Mendel but is himself killed bare-handed by the enraged Dobbs, who uses the cast on his hand as a bludgeon. Dobbs flies to Zurich where he is met at the airport by Ann. ==Cast==