At the height of his popularity in what is sometimes called the Golden Age of Detective Fiction, Freeman Wills Croft was a believer, in first of all when writing a novel, preparing a synopsis of the actual facts that are supposed to have happened including a chronology, character biographies, and sketch maps of the important localities. He followed this with a summary of how those facts were revealed to the detective concerned (and of course to the reader), again with a chronology, and then he was ready to begin writing the book. He follows all those guidelines explicitly in 'The Hog's Back Mystery'. And the mystery is in doubt right up to the last couple of chapters of this novel.
It all begins with a cosy weekend at St Kilda, the cottage in the country just below the Hog's Back, which is a ridge in the North Downs in the beautiful Surrey countryside. It is the home of Doctor Earle and his wife Julia, the doctor being a semi-retired practitioner. Guests arrive, along with neighbours, to enjoy a peaceful weekend but suddenly Dr Earle disappears from the cottage.
Initially nothing suspicious is suspected but when events take a more seriously mysterious turn, all the neighbours are checked to see if they had any idea where Dr Earle was. When this proved to be fruitless, there was obviously something amiss. The local police are called in but their endeavours lead nowhere and the family think they are doing nothing. But they are, because with no notice, Detective-Inspector Joseph French, CID, New Scotland Yard, arrives to take charge.
And take charge he does, questioning all who he thinks might have something to do with the doctor's disappearance. But as he is investigating there are two other disappearances and one seemingly unconnected incident in the nearby Red Cottage, where the Campions live, Doctor Campian being a one-time partner of Dr Earle.
French, working in conjunction with the local police but taking the lead very much himself, eventually decides that there are six suspects and an plethora of alibis. He is unsure who did what, if anything, and, with great difficulty, he sets about working out what he thinks has happened from the evidence he has uncovered.
And in an interestingly planned denouement he discovers the truth as the plot keeps the reader guessing right to the very end.
As is the case with these British Library Crime Classics, Martin Edwards provides an excellent foreword with a slight foretaste of what is to come - so beware in reading it first!