The story was set in an alternative history 1970s, in which Nazi Germany won World War II and England is run by a collaborationist fascist government.
Peter Ingram (Kenneth More) is a writer for a soap opera (also called An Englishman's Castle), which is set in London in 1940, during the fictional Nazi invasion and subsequent occupation.
Peter Ingram is a successful London screenwriter, the creator of one of the most popular television shows in Nazi-occupied Europe, An Englishman's Castle.
When the resistance decides to include in his show the code word that will signal a nationwide insurgency, due to its huge audience, he complies, allowing Sally (Jill) to speak the phrase when it is filmed.
As the sounds of a rebellion against the collaborationist government begin to come through the windows of his office, Ingram awaits the secret police; when someone breaks down the door he turns to stare at the unseen intruder.