Hmm. I don't think I'm the right audience for this one. The basic idea--a psychic who is dragged by the spirits into different times so that he can solve nascent crimes--is right up my alley. But the worldbuilding made me wince. Swain's world is neatly divided into Light (definition: the side of cancer-curers, ebola-fighters, and the protagonist) and Evil (maniacally-laughing serial killers who sell their souls to the Devil and tattoo their bodies with skull-eating demons). The whole basis of the story is a serial killer who is going after women who are aiding the Light by curing cancer, etc. Such simplistic worldviews drive me nuts, especially when they come tied to the idea that it's okay to murder agents of Evil because they're Evil.
The rest of the story doesn't precisely break the mold. Peter has to struggle with a literal inner demon (but don't worry--he's on the side of the Light, after all, so it's okay if he commits a few murders here and there) while dealing with a demanding and unreasonable Muggle girlfriend and doing magic shows for the kiddies. The mechanics of mystery are simultaneously so simplistic that I became impatient with the protagonist and so utterly unrealistic that it demanded more suspension of disbelief than the all the book's ghosts, demons, and gods put together.
One of my major attractions to hardboiled UF is the world of greys. I hate it when things are simplified into a structured Light/Dark duality.
Meh. I read too many books in this genre to be hooked by this one.