Dresden and his friend Michael - a Knight of the Cross - are kept busy. Ghosts are going crazy all over town, and the veil that separates the real world from the Nevernever has been weakening. 
 I've been told that the series really starts to pick up with this book and I think I can see it (though it could just be that I was expecting to like it better so I did. Brains are weird like that sometimes.). 
 The last two books had started to show a predictable pattern: Mystery is introduced, Dresden makes two potions for funsies, Murphy messes everything up because she's blinded by her distrust for Dresden, potions just happen to be exactly what Dresden needs, showdown, The End. But Grave Peril breaks from the formula quite significantly. 
 For one thing, there's two new major characters introduced: Michael Carpenter (aptly named for a devout Christian) on Team Dresden, and Lea, Dresden's Fairy Godmother and most definitely not on Team Dresden. While I found Lea interesting, I did find it strange that she would pursue Dresden so doggedly in Grave Peril yet not make any appearance at all in earlier books. I don't think that this absence was ever explained (or retconned, as the case may be). 
 Potions don't make an appearance in this one, which is a shame because it's the aspect of Dresden's magic that I enjoy reading about the most. However, leaving them out did keep the series from falling into too laughably absurd a pattern, so I suppose it's okay. 
 The last big difference from the other two books is that Grave Peril puts a bit more focus on Dresden's moral choices - the idea of having to choose between a small number of people he cares for and a large number of people he doesn't know, or whether it's worth killing a baddy if it means also killing innocents as well (and what Dresden's share of guilt in such a situation might be). It added an interesting dimension to the series and a little food for thought - though, of course, the questions were merely raised, never answered. 
 Through much of the book, Murphy is unconscious and out of the picture, and I find it sad how much of a relief that was. She's a terrible character. Her propensity to make getting the baddies far more difficult than it needs to be because of her lack of trust has really been getting old. Perhaps even worse is the fact that neither character-Dresden nor narrator-Dresden ever acts like her attitude is a problem. He's always apologetic, accepting his guilt, and seems to believe that being irrational and angry all the time is what makes a strong female character. Compare her to her replacement in Grave Peril, Michael. Michael and Dresden are able to work together as a team, trusting each other when information needs to be withheld, respecting each other enough not to withhold it unless absolutely necessary, and able to protect each other without it being a gender thing. Michael is, in many ways, what Murphy should have been from the beginning. 
 One thing that confused me, and perhaps someone could explain it to me in the comments, is why Dresden mentions the possibility of calling Murphy for backup twice, despite knowing that she was unconscious. The first time he's corrected, but the second time it's just mentioned and dropped. Was that an editing error or did I miss something? 
 Anyways, I did enjoy this book much better. It had a few twists where it seemed to be following a predictable pattern and then veered off, which kept things interesting. I found that the resolution of the mystery was rather flimsy (spoiler: two baddies were working together, though I couldn't figure out why they would do so except for their mutual dislike for Dresden), but that's okay. I enjoyed the ride.