At first glimpse, this book is almost a spitting image of any of the Dresden Files, only with a female protagonist. You have a rich urban fantasy setting filled to the brim with weird things passing themselves off as people, you have a mystery involving some sort of supernatural creature (a zombie, as it happens), and you have a main character who is human... but not quite. Our protagonist, like Harry, has extra baggage back at home, enough to keep her almost dirt poor. The character in question is on police retainer but also has a day job, and while Vivia Brisk works for a non-profit in England instead of a wizard PI in Chicago, the book instantly has a very similar mood and tone.
Then the differences begin to set in, and by and large, these differences are interesting and well-handled by the author. Instead of supernatural creatures operating under the radar of normal folk, they're fully integrated into society. Something nasty has happened to New Zealand, the London police have a unit specifically designed to deal with folks who are set to go full-on ravenous flesh-eating zombie (though they appear to have pretty awful aim), a colony of winged people live up near Scotland on a remote island, and there are activist groups for various different creatures persecuted by the mainstream society (though the sheer number of non-humans in the book leaves the reader wondering where all the normal folk are...)
There are werecreatures, skinchangers, winged, zombies, mages, normal humans looking to enhance themselves cybernetically, and a whole host of other cool beings running around London, and then there's Vivia herself: a hag. With the ability to step beyond the veil and into the land of the dead, Vivia is a prime candidate to help the police in their investigations, especially one in which a zombie is airlifted off the scene of the crime by his winged bastard son, and several desiccated bodies are found near the zombie's house.
From here the mystery deepens, until it's impossible to tell exactly what the mystery is, which is where the book takes a turn for the worse: the cast of characters begins to fill to the brim, then overflow. Taking into account that Vivia could find someone's shade in the land of the dead, and that those people have unreal copies of other people in their death-world dreamscapes, and you have a book that is over saturated with characters that are alive, not alive, not real, hiding something, presumed dead, and possibly the bad guy. By around the sixty or seventy percent mark, the cast of characters has grown so large that it's impossible to keep track of them without a notepad or several family trees.
This is really unfortunate, because there's a great writer here, one who has the capacity to keep things moving and keep the readers guessing. Unfortunately, the author is either well ahead of the reader, or isn't actually sure how the book should end. Even at the end, when the finale rushes off to a bizarre and brutal conclusion, I couldn't be sure what the original crime was all about in the first place.
While I will confess to being a lover of urban fantasy, and while Vivia seems like the perfect character to get involved with homocides and supernatural-related crimes, I can't recommend this book as a mystery. Readers are cautioned to have a notebook ready, for clues and genealogies.
AIA's 4 star rating includes books that would probably be picked up by a mainstream publisher, and the writer's smooth transitions and interesting dialogue/characters place it very close to the mark, but the plot itself is bursting at the seams with characters (alive and dead, real and non), so much so that it's impossible to keep track. AIA's 3 star rating is books we'd recommend as a good read, but which might need some work. The Secret Dead falls into the latter category.