The fourth Mercy Thompson books starts right after the trauma of "Iron Kissed" and then kicks it up a notch by literally dropping a tortured, ravenous vampire into Mercy's arms.
What follows is clever, dual plot novel, focused on vampires and ghosts, that moves the whole series forward.
I was impressed at Patricia Briggs' ability to continue to be inventive in how she shapes the supernatural world. "Bone Crossed" gives me a kind of vampire I've never encountered before. It also succeeds at mixing werewolves, fae, vampires and ghosts in a way that feels credible and doesn't leave me feeling I need a field guide to supernatural beings to understand what's going on.
The main strength of the series is the strong focus on character-driven narrative, not just Mercy's character but for the secondary characters as well. Even the rather unpleasant leader of the local vampires gains some depth in this book. Everyone is granted some complexity that helps make them real.
I also admire the way humour, especially banter, is used to leaven the dark themes of the book without undermining or denying them.
What keeps things fantasy fretwork grounded is the willingness to take a realistic approach to the emotional impact of events. Patricia Briggs acknowledges that, even when you're a kiss-ass heroine coyote mechanic raised by wolves, the aftermath of rape is months of panic attacks that leave you vomiting and curling up into a ball.
She also allowed Mercy to make a choice between the two men who want her. I'm glad we avoided the Stephani Plumb Purgatory of never being allowed to choose one man because unresolved sexual tension sells. I also think she chose the right guy, so I'm smiling (who knew I'd care?).