Shape-shifter Mercy Thompson has a complex life, juggling two werewolf lovers and a job working for a fae mechanic; things get even more hectic when her boss and mentor is arrested for killing a citizen of the fae reservation. As the fae seem content to let him rot, Thompson takes it on herself to clear her friend's name, beginning a lone-wolf investigation that may cost her life. Briggs's third novel featuring Thompson (after Blood Bound) is another top-notch paranormal mystery; her well-balanced contemporary world, where humans live uneasily among werewolves and fae, is still a believably lived-in world; the ever-present threat of government legislation against nonhumans (though familiar to X-Men fans) adds weight to her paranormal elements, and thoughtfully researched mythology adds rich detail. Thompson is a sharp, strong heroine and her lycanthropic love triangle is honest and steamy. Briggs never shies from difficult material, and she moves effortlessly from werewolf pack psychology to human legal proceedings, making this a tense, nimble, crowd-pleasing page-turner. (Jan.)