Murderer's Mistake — E.C.R. Lorac

It's not long after the end of WWII, rationing is still in force in the UK, and Chief Inspector Macdonald of Scotland Yard is hot on the heels of a coupon racketeer, Gordon Ginner. Just then he gets a letter from Lancastrian farmer Giles Hoggett about some odd goings on recently in Lunesdale. Normally he'd pass on the letter to some subordinate, but the possibility that Giles's suspicions might link to the Ginner investigation are just too tantalizing to leave alone, so off to Lancashire goes Chief Inspector Macdonald... soon to discover the murdered body of Gordon Ginner!