This is the third book in the Mercy Thompson series. Although it does repeat enough background that it would probably make sense on its own, you should start with Moon Called, because it's really good. It has a solid enough ending that the series could have ended here, but I know book four is out in hardcover.
This series continues to feature excellent worldbuilding. We get more details about more magical creatures, and it still hangs together as internally consistent. There was a fairly important issue in the last book where I realized that the situation the characters were in shouldn't have worked given the rules we'd been presented. In many author's works, such a thing would have just been an ongoing flaw, but we addressed it head-on early in this book, and actually explained it in a way that makes sense. The political interplay between different species has some ugly parts, but it's consistent and believable.
There's a lot of breathless action in the adventure side of this story, but the really important parts of the story are the romance side. In most books, that would be, if not a flaw, at least a clear indication that this wasn't the book I wanted to read, but it is really well done here. The tension between independence and commitment is so thick that it is difficult to just sit still and read the book. The characters are so real for me that I want things to work out so desperately that I kept finding myself terrified to the point of having to stop and pull myself together, not in the fights, but in the romantic parts.
Really, what keeps this book from being perfect for me is that I'm so emotionally engaged that it kept kicking me out of the story.
9 out of 10.
**** PLOT SUMMARY -- MASSIVE SPOILERS ****
Zee calls Mercy in to investigate a series of murders on the fae reservation. Her sense of smell allows her to defeat the glamour and find her way into Underhill, which she's not supposed to know about, and knowing the fae's secrets is usually deadly. But she does definitively identify the scent of the asshole guard who harassed them at the gate at the murder scenes. She realizes that if she reveals this, she'll be condemning the man to fae execution, but she does it. Zee and Uncle Mike go to the guy's house, only to discover that he'd already had his head torn off, and the police show up before Zee can get away. The Grey Lords plan to sacrifice Zee to keep humans from looking more deeply into the matter, but Mercy refuses to let that happen. She arranges to hire a high powered lawyer, who turns out to be a member of the John Lauren Society, a radical anti-fae group -- which only increases her effectiveness in the defense, since people would assume that she'd only be willing to represent her enemy if she actually believed him innocent. Samuel gives a concert at the local folk festival, where Mercy meets Tim, who appears to be a badly repressed geek but someone she can actually have an intellectual conversation with. She also finds out that he's involved with Bright Futures, a second anti-fae group, and decides that even though it's going to bother her would-be boyfriends she needs to check him out. The group seems to be pretty harmless, but then she discovers she's being followed by Fideal, who was the faculty advisor to the Bright Futures group before they changed their focus. He turns out to be The Fideal, a nasty child-eating monster, who didn't get the message that Mercy has protection. Mercy manages to lead him to Adam's, where the wolves drive him off, but not before he drags Adam into the river where he almost drowns (the wolf form, it seems, is too dense to be able to swim), but is rescued by Peter, who'd stayed human to try to fight the Fideal with a sword, but is foiled by its protective layers of seaweed. (Peter, we discover, is very old, maybe older than Bran, and learned to use the sword in pre-Revolutionary times. Submissives are more likely to live a long time than dominants.) In spite of the fact that Mercy is actually in physical danger, she objects to having a bodyguard with her, so Adam installs state of the art electronic security systems at her trailer and her garage. Mercy has learned that there are several missing ancient fae magic items, and even more important, a list of items and who has them. Even though the fae don't want her to, she's determined to keep investigating. She'd intended to be done with Tim, but then he drops a hint that he might still have a clue about the missing items, so she goes to his house. He bespells her with an ancient cup; when someone drinks from it they're supposed to be unable to resist the commands of the holder. Her walker nature keeps letting her start to break free, but he keeps telling her to drink more. He's about to rape her but she tells him about the staff which she first saw when she was investigating the murders and which has started following her around, appearing in places where she'll find it by its own magic. She takes him to her garage and gives the alternate "I'm a hostage" alarm code. He rapes her, physically but much more importantly mentally, telling her that she will never be loved and should just kill herself. She is able to grab the staff and kill him, and just then Adam shows up and tears him to shreds on his own security cameras. The fae recover the artifacts, and the scene of Mercy being raped is enough to get everyone off the hook legally, but Mercy is badly broken. Her arm has been crushed, far beyond natural healing. The cup, controlled by a fae, can heal her, but she won't drink again. Adam uses his powers to force her, but this only makes matters worse for her mentally. She's incoherent and cowering, and Adam believes he's lost her and can't help when Ben stands up to Adam and gives him a lecture about what Mercy is really feeling, a lecture that she can't give because she's in coyote form and much too messed up to talk anyway. Adam pulls her out from under the bed and holds her until she starts to believe that he really loves her.
Back to the beginning, to cover the romantic plot. Mercy realizes, right at the beginning, what was bothering me at the end of Blood Bound: Samuel and Adam shouldn't be tolerating each other so well when they're both trying to win Mercy as a mate. Worse, Mercy learns that when Adam claimed her as a mate, it wasn't just werewolf politics, it was for real. Until she either accepts him or definitively rejects him, he is emotionally weakened and is less in control of his wolf. She considers Samuel's suit first, and while she realizes that she does love Samuel, she simply could not be his mate; she is absolutely sure that he would smother her in his controlling protectiveness. If Bran hadn't stopped her from running away with him when she was 16, the person she was then could have actually made a life with Samuel, but the strong, independent grown up Mercy couldn't. She's trying desperately to figure out how she can tell Samuel this without breaking him when he manages to admit that his wolf has already given up and no longer considers her his mate. He's insisting on living with her in her trailer, not because he thinks he can be her mate, but because he needs her as his pack. He can't join Adam's pack because he's more dominant than Adam; he has no desire to depose Adam but wouldn't be able to be subordinate in his pack. Fortunately, the two of them like and respect each other enough that his being around, officially a lone wolf, has worked out, but Samuel can't be truly alone. Living with Mercy is keeping him sane. Having accepted that she can't possibly live with Samuel, Mercy is now terrified that she can't put off resolving things with Adam any longer. She has a little more hope that Adam won't smother him with his protective care, but he's still a very controlling presence and she's not sure it will work. But at the end, after Mercy has had to have Adam and the pack save her life twice and after he's held her together after she was raped, he insists to her that by going to him for help, she has decided. If she runs away now, he promises he will track her down and bring her back. And she seems to finally believe it; in the last line of the book, she's finally taking her clothes off to actually have sex with him.