In Lord Peter Wimsey's debut novel, Dorothy L. Sayers provides her detective with quite the conundrum: a known missing body as well as a found unknown one. While the modern reader won't likely be puzzled by whodunit for long, the story is still an enjoyable read. While the class distinctions seem anachronistic - at least in 21st Century America - I can see that the story could have easily been a sensation for the time and place it was written.
In addition to introducing Lord Peter, we also meet his mother, the Dowager Duchess, and his brother, Gerald, the Duke (sadly, his sister, Lady Mary and nephew, Gherkins, don't make an appearance in this book), as well as his future brother-in-law, Parker, the Honorable Freddy Arbuthnot, and, of course, the indispensable manservant, Mervyn Bunter. While all of the characters have some growing to do as the novels progress, Lord Peter's relationship with Bunter is firmly established here. There's little wonder Sayers' series became a hit and has continued to be enjoyed down the years.
While the "mystery" portion of the book isn't the most challenging, Sayers includes a few entertaining tangents, like the one about the future of mankind's vestigial conscience (which includes an aside about "backwards individuals" like myself who can wiggle their ears). I enjoyed her philosophical/theological musings here (and moreso in her non-Wimsey mystery, Documents in the Case), and wish she had included more of them in her later novels.
If you've never read any of the Wimsey novels, this is a great place to start. The villain is well-constructed, if insufficiently hidden, and the story has a charm that, while old-fashioned, is charming nonetheless.