Taking a very Noir feel to the whole Eberron world, the City of Blood story allows you to jump right from the Eberron given story into this crime scene story. I wish that there were actual crime scenes included along with the pictures of the individuals found, but through some googling, it wasn't that hard. The one thing I wish that it went over a little more was some criteria for a certain tool, SPOILERS the dagger. When it changes the person into the other, I added that the amulet also had to be used in conjunction to make sure that this was not a broken mechanic.
Other than that, a great mystery that if you put on some Noir jazz will have all your players thinking they are in Chicago or some other noir movie landscape.
[5 of 5 Stars!]