Plenty Under the Counter by Kathleen Hewitt

London, 1942. Flight-lieutenant David Heron, home on convalecent leave, awakes to the news that a murder victim has been discovered in the garden of his boarding house. With a week until his service resumes, Heron sets out to solve the murder. Drawn into a world of sytery and double-dealing, he soon realises that there is more to the inhabitants of the boarding house than meets the eye, and that wartime London is a place where opportunism and the black market are able to thrive. Can he solve the mystery before his return to the skies?