Michael Innes (J.I.M Stewart) is one of my favourite Golden-Age writers and there was a time when I read his books one after the other till I ran through all the titles the various libraries (I frequent) had on their shelves. After all these years, the titles and the plots are a little hazy but one I remember enjoying immensely is Hamlet, Revenge!*
First published in 1937 - with war-clouds gathering once again - the book combines elements of a who-dun-it with the spy-novel. The setting is one I particularly love: an old country-house. Scotland Sleuth (and Innes' Detective-Hero) John Appleby, is present in Scamnum Court, the seat of the Duke of Horton, during the presentation of an amateur production of Shakespeare's Hamlet when the staged death of Polonius turns real. The Lord Chancellor who is playing the role is shot dead right at the moment when Hamlet is about to run his sword through him. Since the Lord Chancellor was involved in some hush-hush affair regarding England's defence, the safety of the country is suddenly in jeopardy. A number of deaths occur next (including that of an Indian Bengali Academic) as Appleby matches wits with a murderer who challenges him by sending cheeky notes.
Entry for letter H in the Crime Fiction Alphabet Meme.
* The book I have now discovered is on the Bloomsbury 100 Must-Read Crime Novels.