
The Secret Detective Agency by Helena Dixon
The Secret Detective Agency has a good set up. We're in London in 1941, right in the middle of WW2. Jane Treen, a mid level spymaster working in Whitehall, is concerned because several of her agents who were connected with Operation Exodus have been murdered. There seems to be a mole in their midst. Most recently, Kate Trevellian was murdered in a small village outside of Exeter, at Half Moon Manor, the home of Arthur Cilento. Arthur, conveniently, is a mathematician and codebreaker who also works for the government. Arthur had been renting the house out to Kate, and he has just returned home, so is not a suspect. Jane's boss sends her to Half Moon Manor to work with Arthur to figure out who murdered Kate and uncover the plot to kill off the remaining Operation Exodus spies.
Jane and Arthur are total contrasts to each other. Jane is intuitive, on the move, and a chain-smoker (as we are...