An Englishman's Castle.

In an alternate 1978 wherein Germany won World War II and has occupied the United Kingdom, successful television writer Peter Ingram works on a popular soap opera, An Englishman's Castle, set in Blitz-era London. Ingram lives a quiet, boring life, deliberately oblivious to the subtle rule of the local Nazis. His eyes are opened when the woman he is involved with reveals that she is not only a Jew but also a member of the Underground.