Twenty-fifth in the long-running mystery series with Dr Launcelot Priestley. >Every year, for a month or so, a crowd descended on the village of Culverden every weekend. They came primarily from the poverty-stricken East End of London, to visit the countryside and to make a bit of money picking hops. They stayed in huts away from the village dwellers, drank outside the pub rather than inside – unwelcome in some ways but a vital part of the economy nonetheless. >Then one night Sergeant Wragge happened to see something unusual lying by the side of the road, and decided to take care of it himself. After all, a twelve-inch butcher knife is nothing to be left loose on a public highway. When he noticed those curious stains on the blade, his suspicions were more than aroused and he felt that he must be ready for trouble. >The Sergeant’s forebodings were swiftly corroborated by the events that followed - robbery, a mysterious disappearance, perhaps murder; so he felt that he was justified in demanding the aid of Scotland Yard. The careful investigations of Inspector Hanslet and Jimmy Waghorn soon had them on the right track; but it was Dr. Priestley’s quiet, seemingly enigmatic suggestion that finally unearthed the solution.