Barrister Francis Pettigrew is away from his chambers to act as legal advisor to the wartime Pin Control Authority (Yes, really, Pin Control). This is of course a fictional authority, so no problems with secrets, defamation etc. A country house mystery, elegantly written and with, as usual for Pettigrew and his barrister author, a lesson in the arcana of the law of England and Wales. Interestingly (to me, at least, in Wales), there are details to suggest location in perhaps Barmouth or Harlech, though this is also disguised, as Marsett Bay.
Fun, in a very 1940s style.