Lord Peter is clearly eccentric, and wealthy. He has a fabulous flat, collects rare books, and owns a large private car in the early 1920s. He also investigates crimes - not a gentleman's job at a time when gentlemen were defined by not having jobs. His frightfully conventional brother, the Duke of Denver, abhors his hobby but their mother, the Dowager Duchess, takes a more favorable view. It's the Dowager Duchess who calls Lord Peter when the architect reconstructing the local church finds a naked corpse with a pair of pince-nez glasses in his bath. Lord Peter investigates, and finds that the body is probably not that of the affluent man he's been groomed to appear to be. Also investigating the body is Inspector Charles Parker, who is investigating the case of a missing financier who roughly fits the description of the body in the bathtub. The body is not that of Sir Ruben Levy, but Lord Peter finds too many coincidences to believe that the murders are unlinked.
I've read Whose Body at least twice, so I know who did it, but that didn't diminish my enjoyment of the novel. Sayers deserves her place as one of the grand masters of the golden age of mystery. Her Wimsey novels are cleverly plotted, with memorable characters (and even more memorable names - Inspector Sugg, Sir Julian Freake) and the right balance of clues and obfuscation for the reader to solve the mystery but not feel stupid if stumped.