The novel begins in December 1940 with the return of Sergeant Nick Penny to his home in an unnamed
West Country port town. A former
prisoner of war, he had been captured in the aftermath of the successful
German invasion of Britain. A former schoolteacher, his ability to speak German had secured his release to work as a
translator for the military governor of region,
Generalleutnant Kurt von Glass. Glass soon puts Penny to work in organising the "Anglo-German Friendship League", which is designed to foster greater unity. Penny is uncomfortable with his current position, and is viewed with suspicion by much of the community. Soon after his return, he visits the Three Horseshoes, a local pub operated by the family of his friend, Roy Locke. There he reconnects with Locke, who immediately begins to recruit him for the emerging resistance movement. Penny begs off, requesting time while he sorts matters out. Penny soon finds himself drawn into the resistance, motivated in part by the gradually increasing harshness of German rule. Penny's mother and sister, with whom he lives, suffer physically and psychologically from the effects of German rule, while Penny's nephew, David, desires to strike back. Though Glass supports Penny's suggestions for fostering Anglo-German amity, the region's security chief,
Standartenführer Stolz, is using every pretext for brutalising the local population. Penny and Locke nearly miss curfew, but are saved at the last minute by the timely arrival of Matty Cordington, their old friend, who was released from
internment and who brought Sara Burskin, a
Polish refugee, with him. Roy quickly enlists them into a plan to smuggle the
Regent,
his wife, and the
crown jewels out of the country, but they are thwarted by the
Abwehr. Though Penny and Cordington manage to evade capture, Locke is arrested but kills himself before revealing any information. After their failed operation, Penny loses contact with the resistance. Loathing his life, he watches as profiteers like the local
newsagent reap the benefits of the growing crackdown on Jewish businesses. In March, however, the German
invasion of the Soviet Union breathes new life into the resistance as
Communists now join the effort. Penny is contacted once again by Coral Kennedy, a young woman whom he met during the failed effort to smuggle out the Regent and the jewels. Once again involved with the resistance, Penny assists in a number of their operations, informing Kennedy of an attempt by the
IRA to assassinate Glass and helping to smuggle a
Danish scientist and his wife out of the country. Yet these are isolated successes amidst a series of setbacks, as the Germans disrupt operations and shut down networks. Glass himself soon leaves Britain to serve on the
Eastern Front; his departure coincides with the
roundup of foreign-born Jews by the authorities, including one in hiding on Cordington's estate. A ruse by the resistance reveals the leak: Sara Burskin. Informed of this discovery, Cordington agrees to kill her himself. The discovery of the leak leads the resistance to abandon contact with Penny yet again, as the German security services are clearly aware of his participation in the resistance and hope by monitoring him they can discover the identity of other members. Penny is therefore surprised when Kennedy suddenly contacts him in July with a new mission: to smuggle out
Otto Frisch, who the
Gestapo has discovered knows information which could be vital to the development of a "
superbomb". Travelling to
Liverpool, they succeed in persuading Frisch to agree to escape. Avoiding discovery, Penny hides Frisch among the Jenner family, where he poses as a visiting relative. The Germans order a second round-up of the Jews, though, this time including native-born British citizens. Frisch is captured along with the Jenners, and Penny and Cordington travel to
Imber in order to stage an escape from the
concentration camp the Germans have built there. Upon their return Cordington tells Penny about his plans to meet with a nearby resistance leader, followed by a trip to London for an upcoming conference to resistance leadership to be held during the Regent's re-
coronation. After he leaves, Penny is sent to intercept him and to head-off an ill-advised ambush that threatens to draw in a nearby
Waffen-SS unit. Penny arrives in time to save Cordington but not to stop the ambush, which leads the Germans and their British auxiliaries to massacre everyone in the nearby town of Merricombe in response. He returns with news of the massacre, which Kennedy quickly exploits for propaganda purposes. When they attempt to smuggle Frisch out of England, however, they are met by Sara, who is very much alive and who reveals that Cordington is in fact a
double agent who was coerced into working with the
Gestapo upon the discovery that his deceased mother was in fact Jewish. Killing Sara, Penny and Kennedy race to London to prevent Cordington from revealing the location of the resistance meeting to the Germans. Pursued by the authorities, they make it to London and warn the resistance, but they are unable to stop Cordington before he executes his real plan: using the credentials given to him by the
Gestapo to get through security at the coronation and setting off a suicide bomb that kills the Regent and assembled German leadership. In the aftermath, the Germans retaliate by massacring over 100,000 people (including Penny's remaining family), triggering a nationwide rebellion that threatens the Germans' hold on their empire. ==Characters==