Ferguson lived for a time in Guernsey and the island provides the setting for Death Comes to Perigord. And a very effective setting it proves to be. The smallness of the island allows the local police to be quite sure that certain key players in the mystery either did not leave the island, or did not enter it, at a critical time period and this provides very important clues. It’s also a nicely colourful and slightly exotic and interesting setting for a murder mystery - Guernsey is a possession of the British Crown but it is not part of the United Kingdom and it has its own laws. It’s also (or at least was in 1931) partially bilingual and Ferguson makes use of this as well, with French underworld slang providing important clues also.
The novel is narrated by Dr Dunn, a young Englishman serving as locum tenens for a local doctor. The fact that Dr Dunn is not a Guernsey native will also have some importance. Dr Dunn has been asked by the avocat (as lawyers are known on the island) Le Marinel to look in on one of the island’s wealthier and more irascible residents, Hilaire de Quettville. The man seems in perfectly sound health for a man in late middle age and Dr Dunn is rather puzzled as to why Le Marinel was keen to have de Quettville checked up on.
Now things start to get a bit strange. A superstitious old woman had convinced herself that a decaying ship’s figurehead in the form of the god Neptune is actually a statue of a saint. This Neptune is then stolen and placed over the gateway to de Quettville’s estate. This is interpreted by de Quettville as either a mortal insult or possibly even a threat. And then de Quettville simply disappears.
Dr Dunn would probably have given the affair little thought but the fact that he was called in to attend de Quettville means that the vanished man is his patient and he therefore has a certain responsibility. He’s also quite intrigued. Guernsey has turned out to be a place in which odd things happen and a place inhabited by people with surprisingly strong and unpredictable passions. What really gets Dunn’s attention is an attempt on his own life. At this point he makes a rather wise decision - he asks his friend McNab to join him on the island as soon as possible. Francis McNab is a private detective and Dunn has assisted him in a number of his investigations. Maybe McNab can make sense of things.
At this rather late stage there’s been no actual crime but that is about to change. And McNab notices a couple of very important points that the Chief Constable has overlooked. Not only has there been a crime, the crime is almost certainly murder.
Murder has been committed but both the method and the identity of the killer remain mysterious. The most promising suspects have unbreakable alibis. The medical evidence had at first seemed to be ambiguous. When the ambiguities are resolved it just makes things worse since it makes those alibis absolutely unbreakable. The medical evidence also raises perplexing questions about how the murder was done. To cap it all off there are completely unexplained elements - there can be no possible rational motive for the attempt to kill Dr Dunn.
This is a plot with the complexities that are so beloved by devotees of this kind of mystery, and Ferguson resolves those complexities convincingly enough. The trick to pulling off a successful golden age detection story is to ensure that while various plot elements might be unlikely or even outlandish the reader will accept them as being within the bounds of the possible. Ferguson succeeds in doing this.
Is it fair play? I’d say that yes it is. The clues are there and they’re hidden in plain sight.
And is it enjoyable? Again the answer is yes. There’s an absorbing mystery with some nicely odd features and as a bonus there’s an exciting action climax (which betrays the fact that the author also wrote thrillers). Highly recommended.