The third Lord Peter Wimsey novel. With rather few connections to the others -- you could not tell its place among the early ones on internal evidence alone -- though my edition opens with a biographical note purportedly by his uncle to recount his backstory, and it alludes to later novels.
But this one opens with Lord Peter and Charles Parker talking in the restaurant about doctors, and what they may suspect, and what they can prove, about odd deaths.
Which happens to be overheard by a young doctor, who can give them a similar account, and what happened when he made too much of a stink. Without the details, of course. Nevertheless, Lord Peter, after holding forth on how easily murder could be committed if only murderers carefully selected victims and means and situations, decides to investigate. Even though the most likely murderer, the woman's niece, has no apparent motive, since she would inherit regardless.
He takes Parker around to meet Miss Climpson, a middle-aged spinster he retained to act as an investigating agent -- the most natural person in the world to gossip. Things accelerate from them. It involves discussions of the long-lost heir from overseas, an uncle who became (shush) a monk, a black cousin stemming from a black sheep of the family taking out overseas, poultry farms and alibis, talking with lawyers about newly passed Acts, and much more.