This was an enjoyable read, but not outstanding. While the plot was full of satisfying twists and turns which kept the reader guessing, I felt that the characters were a little two-dimensional and cliched. This contrasts with some books that I've read recently, where the characters have been complex, but the "whodunnit" elements have been secondary. I could well imagine this turned into a pretty ghastly made-for-tv movie.
It did hold my interest enough to be curious about the first book in this series, "The Railway Detective" however.