Dorothy L. Sayers
In this, the first of Sayers' Lord Peter Wimsey mysteries, we are introduced to the gentleman by a strange method; a body is found in someone's bath, and Lord Peter's mother asks him to get involved, as she feels the introverted man whose house it is will be bullied by the police. (This is actually a fairly justified fear as the policeman in charge is the sort to draw the "obvious" conclusion by ignoring all manner of evidence.)
Lord Peter is portrayed as somewhat flighty and like his surname; he is assisted in his crime-solving efforts by his steady butler Bunter, a Jeeves type to Peter's Wooster. Of course, the first problem is finding out why a naked man was slipped into someone else's bath; it is necessary to determine who the person is, and more importantly, what this has to do with the disappearance of a finacier who superficially resembles the corpse.
As this is an introductory novel, there is much time spent on the development of characters and their interactions - somewhat to the detriment of the plot. Moreover, there are a few character notes which almost feel forced into the narrative; while it is important that Lord Peter served in the war (WWI) and suffers from "nerves" (post-traumatic stress disorder, a classic case), its introduction and resolution seem somewhat abrupt, and only lightly related to the narrative.
Nevertheless, this is an entertaining mystery in the classic style, and an introduction to one of the classic characters of mystery.