Can people learn to leave the past behind them, and move on? Flora has tried hard to do this but her wartime past as a secret agent just won't let go of her. The spymaster she knew then seems to be pulling the strings again as an old adversary reappears in her life. Meanwhile her friendship with Oliver Quest goes through a difficult patch after a silly argument. He takes on the task of looking after a very special painting belonging to an important industrialist and she looks for a job as a typist.Soon they are both working on different aspects of the 1951 Festival of Britain, and they unexpectedly find themselves in the middle of a murder mystery. Even after a last-minute crisis in the Lion and Unicorn Pavilion is apparently resolved, they find their investigations have to continue.For a while it's as if the pieces from two jigsaw puzzles have got mixed up and will never be sorted out again.