Holy Disorders was Edmund Crispin's second book, written in 1945 and published the following year, but set in wartime, and featuring German spies as well as Gervase Fen. It begins with a young composer called Geoffrey Vintner receiving a bizarre warning not to accept an invitation to travel to a small town called Tolnbridge to play the organ. An equally bizarre telegram from his old friend Fen asks him to buy a butterfly net.
When Geoffrey obediently goes to a department store to purchase the net, he is attacked, only to be rescued by a young man who works there, and whose name, he says, is Henry Fielding. He also reveals that he's a member of the aristocracy. What's more, he accompanies Geoffrey to Tolnbridge to help him find out what on earth is going on.
One organist at Tolnbridge has already bitten the dust, and before long there is another tragedy. Fen is as exuberant as ever, and irritatingly keeps saying that he knows what is happening, while refusing to reveal the truth to Geoffrey or the police. This know-all behaviour was, of course, a feature of Great Detectives - Hercule Poirot was apt to tease in similar fashion - but Fen rather overdoes it.
But that doesn't detract from the enjoyment of a complicated mystery with a startling "least likely person" solution. You don't read Crispin for the characterisation, and the main villain wasn't really believable to my mind, but there is more than adequate compensation in the witty writing. There's even a cluefinder element - footnotes to the closing pages referring the reader to the clues in earlier chapters. Great fun.