In this tale, we follow along as Lenox and his faithful sidekick Graham try to solve the crime surrounding the appearance of a very dead body on a train. Along the way, favorite regular characters such as Lady Jane and Lenox's brother Edmund appear to fill out the thoroughly enjoyable, and I would argue best of the three prequels, tale.
For this novel, Finch draws on America a little to supply some of his characters, and the approaching Civil War and the issue of slavery are frequently discussed among the characters--as is the issue of Charles' love life. If you have read the other books in the Charles Lenox series, you'll know how this ends, but this knowledge does not prevent the attempts at society to marry him off to every eligible and willing woman from being a welcome and entertaining diversion.
If you have read the other books by Finch that make up the Charles Lenox series, you'll definitely want to get this to fill out the prequel set and see it connect thoroughly to the series. If you are unfamiliar with Finch, get yourself The Woman in the Water and The Vanishing Man and read quickly so that you can be ready to go on publication date.