Throughout Appleby’s series, he goes from being a promising young Scotland Yard detective, handed the most confusing cases, trusted to behave appropriately among the aristocrats; moving up through the ranks, marrying the clever Judith, and retiring only to find himself almost immediately confronted with a murder practically on his doorstep.

In this book, he is 60, long-retired, a little (Judith worries) bored.

But the book doesn’t start with Appleby, it starts in a 1st Class Train Carriage containing two people: Priscilla Pringle, a mystery writer who sets her mysteries among the clergy (Murder in the Cathedral, etc.); and a man that, she can’t help but notice, is reading her latest book (in paperback format, unfortunately for her royalties) and then – to her dismay – he pencils a grade of B-?- on the last page – practically a C! On her book!

When she probes in a gentlewomanly way, he confesses himself impressed by her ability to write and claims the mark is not for her book but as a reminder to himself to apply that grade to one of his students when he arrives home, for he is a “crammer” – a retired military man who makes a living “cramming” enough knowledge into young gentlemen who are intellectually unfortunate, in hopes of getting them into what would be, for those attending Oxford and Cambridge, safety schools – and then into the military.

But then the conversation takes a turn: the man offers Miss Pringle £500 to partner with him on a murder – a mystery, of course – set in the town where he lives, perhaps the victim being the squire who lives next door to him. It’s an odd conversation and not at all Miss Pringle’s cup of tea. The man seems mad and persists in soliciting her assistance in figuring out how best to kill off his neighbor – in print, of course, she queries, to which he insists, yes, yes, of course, on paper only. She manages to elude him when their train arrives in London, escaping with his visiting card (like a business card, but with his home address).

Miss Pringle is in London for a club dinner, the club being a group of mystery writers, the guest of honor that evening being Sir John Appleby. When Appleby is introduced to Miss Pringle, the author she had dined and shared her story with, starts to share the amusing anecdote with Appleby but barely has he heard the gist of a man in a train carriage feeling out Miss Pringle about committing a murder, when Miss Pringle cuts her friend off and refuses to discuss it further. Appleby shrugs and moves on to the high table, where he is reunited with a woman he had know as running a very capable government department involved in espionage and, it appears to his surprise, writing mysteries. And then she mentions meeting a retired military gentleman who is employed as a crammer, in a 1st class carriage, who appears to be curious about crime, in particular, blackmail.

Appleby’s curiosity is piqued but, since the second woman immediately tore up and discarded the man’s visiting card, and Miss Pringle is unwilling to discuss it further, he lets it go.

The action then moves back to Miss Pringle who we find, several months later, visiting the town where the crammer resides. What is she doing there? She makes enough money from her books that she could afford her cozy home in a small country town, live there comfortably, and manage a couple of continental vacations each year, as well as several visits annually to London, where she enjoys in comfort. (It is clear, however, that while her profits allow her to visit London, they are not high enough to allow her to live there – as most American mystery writers would say about living upstate or in further New Jersey and visiting New York.) She couldn’t possibly be considering his £500 offer, could she?

Whilst visiting, she meets the vicar manages to discover that there is a mystery about the death of the previous vicar who had also preceded the crammer in his post. (The vicar ended up down a well in the garden – did he fall, jump, or was he pushed?) She meets the wife of the prospective victim. She interviews the two young men that the crammer is cramming – two young men who claim that the crammer entrapped them using a local young woman and is blackmailing them to assist him. And she has a mysterious second conversation with the retired military gentleman in his home, where they discuss their partnership in crafting the “mystery’ that they will work on together.

Is the man truly planning murder? Why is Miss Pringle agreeing to work with him? And what will she do next?

Sir John Appleby, after his introduction at the start, returns about half-way through, dragged to that same village by Judith who wants to visit an old school chum who lives there. It seems that Appleby had a good handle on what is going on – but even he doesn’t foresee what happens on almost the very last page.

This is delightful book, very clever and witty, with gentle pokes at Innes’s colleagues in the mystery-writing industry. Similarly you get Barnard writing about Romance Writers, and Innes writing about Miss Pringle, and Martha Grimes introducing mystery-writer Polly Praed, and Sayers making Sir Peter Whimsey’s love interest, Harriet Vane, a mystery writer.

Well, I guess they tell you to write what you know…