On the whole not a bad book, but it didn't strike a chord with me. The story was lacklustre and the writing, while at times good, was also pretty bland. That’s Underground’s major problem: I couldn’t bring myself to love it, nor could I let myself hate it. It’s mediocre.
Harper Blaine, the female once-nearly-dead PI with a touch of magic, is a fairly likable character. She doesn’t get on my nerves the way some “hard-boiled” PIs can, swooping in and out of the scene like they’re always in charge; Harper actually seems to have a sense of restraint. However, she isn’t quite as charismatic a character like Harry Dresden. Moreover, she always seems “on the job” even when she’s “off the job,” and the narrative of Underground is frustratingly linear. We're dragged by Harper from scene to scene as she pieces together every single part of the puzzle, with very little in the way of diversion or even a red herring.
As far as the story goes, the mystery and mystical elements are fine. Richardson uses her native Seattle as a suitable backdrop, tweaking the history when she feels it's appropriate, which I don't mind. I never really got chills; I never felt a sense of suspense or danger for Harper or any of the other characters. Richardson attempts to create a particular atmosphere around her homeless characters, showing us a glimpse of this alternative—not usually by choice, of course—lifestyle and its repercussions. It doesn't quite work, though.
I also couldn't get behind Richardson's pet magic, the Grey. It's an interesting concept; I'll give her that much. However, I don't think she describes it or ascribes enough of a fantastical element to it to make for good storytelling. The Grey is more plot device than an aspect of Harper's world. Now, Richardson comes close—I feel like she chooses to focus on the wrong things. For instance, when Harper pays a visit to her friend, who happens to be a witch, Richardson fails to evoke a particular atmosphere. A witch's house should be a place of power (and this in fact comes up in relation to the plot, but not to the scene).
Although I'm not recommending this series to anyone in particular, I also won't advise against it. Underground has very little to offer me and didn't entertain like I had hoped it would, but others may disagree. It just didn't excite me.