In 1950, Juliet Armstrong, a producer of children's programmes at the
BBC, sees Godfrey Toby, a man she knew during WWII. When she approaches him he denies knowing her. The incident causes Juliet to reflect back to 1940 when she was a young 18-year-old woman who had recently been orphaned. Hired to work at
MI5, she is quickly scouted for an operation run by the elusive Perry Gibbons. Working out of two flats, the MI5 team reveal that they are spying on a group of low-level Nazi sympathisers who report to MI5 spy Godfrey Toby, believing he is a secret spy for the
Gestapo. The walls are bugged with microphones and Juliet's job is to transcribe the audio recordings of their conversations. Juliet develops a crush on Perry, who seems to encourage speculation that they are having an affair but does not return her affections. Instead he recruits her to ingratiate herself to a woman named Mrs. Scaife, hoping that she will lead them to the Red Book, a rumoured ledger containing the names of influential Nazi sympathisers. Juliet is given the false name Iris Carter-Jenkins. She is also approached by Oliver Alleyne, Perry's boss, who asks her to spy on Godfrey. Juliet does so, but despite noticing Godfrey acting suspiciously does not report back to Oliver. While searching for the Red Book in Mrs. Scaife's house Juliet accidentally leaves behind her handbag, containing her real identity card, and asks Mrs. Scaife's maid, an orphan named Beatrice Dodd, to help cover for her. A few days later, Perry
proposes to Juliet, who doesn't realise he is gay. The following morning Juliet is sought out by the police who believed she was dead as they found the body of a young woman with her identification papers. Juliet realises that the body is Beatrice Dodd and is frightened as the location her body was found in was one mentioned by Godfrey Toby's Nazi sympathisers. A few days later, Juliet takes part in a sting operation during which Mrs. Scaife is arrested. By 1950, Juliet is working at the BBC. After the war, the operation, and her relationship with Perry, had quickly dissolved. However, she still has MI5 ties and allows her apartment to be used as a safe house for Soviet defectors. At work she receives an anonymous note saying 'you will pay for what you have done'. Juliet grows paranoid, believing the note comes from one of Godrey's recruits. During the war she had been involved with a murder. In a flashback, we are told that after Mrs. Scaife's arrest, Juliet, Cyril and Godfrey were involved in killing Dolly, one of the low-level Nazi sympathisers, after she accidentally discovered their operation. However, Juliet shot to disable her, and it was Godfrey who 'finished her off'. None of the other living members of the circle ever discovered Miller's involvement. On her way home from the BBC Juliet is attacked, but is relieved to find that her attacker is a former spy named Nelly Varga who was persuaded to work for MI5 after they kidnapped her dog, a dog Juliet was put in charge of which later died. Returning home Juliet finds a mysterious visitor waiting for her, a man she had seen leaving messages for Godfrey's, and she now realises she was being spied on for years by MI5. The reader learns that she was a double agent for the Soviets, recruited at her MI5 interview. She had photographed documents in the case of a Czech defector when he slept in her supposedly safe house. Godfrey's colleague persuades her to betray her Soviet handlers. Juliet realises she will never truly be free of either party. She tries to escape but is quickly caught at Dover train station by MI5 agents. However, Nelly Varga attacks her a second time, and the two agents are disoriented allowing Juliet to escape. Perry picks her up in his car and drives her to Lowestoft where she gets a trawler to
Holland. Thirty years later, MI5 forcibly repatriates her to help flush out other Soviet spies, including Oliver Alleyne. By this time she has an adult son. In 1981, shortly after being repatriated, Juliet is hit by a car and dies. ==Characters==