The action in the book centres on Sophia, who seems to have a sentimental and unrealistic view of life. She chooses a husband because he matches her romantic ideal, and he chooses her because she will be an impressive hostess and help advance his career. They are not suited to each other, but never consider divorce and each take up with other lovers. This is all done without any sense of emotional involvement, and no concerns about loss, loyalty or betrayal, and this gives the book a curiously detached feel. It feels unreal and flippant; the language makes it seem a little like Enid Blyton for adults. Sophia's husband Luke represents those in pre-war England who admired Hitler, believed his assurances, and felt betrayed and disillusioned when he made an alliance with Russia and declared war on England. In a sense then I wonder if he is being painted as a pale version of Unity Mitford, who was in hospital as a result of her suicide attempt when this book was being written.
The story moves on to become a bit of a farce, when Sophia becomes aware that Germans are using her house to plan the destruction of London, and she must act to thwart them. She is an endearing character and loves the idea of being a spy, but she lacks the temperament, being rather dense, self obsessed and not lazy so much as coddled, so that she has always been able to avoid doing unpleasant things, and that isn't about to change. But this gives the book its humour, and she comes through in the end.