On the streets of Boston, the world is divided into the ordinary Usuals, and the paranormal Unorthodox. And in the Department of Unorthodox Affairs, the Auditors are the magical elite, government-sanctioned witches with spells at their command and all the power and prestige that comes with it. Grimshaw Griswald Grimsby is…not one of those witches.

Atticus O’Sullivan, last of the Druids, doesn’t care much for witches. Still, he’s about to make nice with the local coven by signing a mutually beneficial nonaggression treaty - when suddenly the witch population in modern-day Tempe, Arizona, quadruples overnight. And the new girls are not just bad, they’re badasses with a dark history on the German side of World War II.

Cutting a deal with a trickster god rarely goes well for any human brave or foolish enough to try it, but Atticus doesn’t feel like he has a choice. With members of the Norse pantheon out for his blood, he can’t train his apprentice in peace, so he asks Coyote to help him fake his own death. The cost, however, might wind up being every bit as high as if he’d made no deal at all.

Thor, the Norse god of thunder, is worse than a blowhard and a bully - he’s ruined countless lives and killed scores of innocents. After centuries, Viking vampire Leif Helgarson is ready to get his vengeance, and he’s asked his friend Atticus O’Sullivan, the last of the Druids, to help take down this Norse nightmare.

A call from a distraught wife, and another from Lt. Murphy of the Chicago PD Special Investigation Unit makes Harry believe things are looking up, but they are about to get worse, much worse. Someone is harnessing immense supernatural forces to commit a series of grisly murders. Someone has violated the first law of magic: Thou Shalt Not Kill. Tracking that someone takes Harry into the dangerous underbelly of Chicago, from mobsters to vampires....