The biting winds of a Chicago winter are scarcely colder than the chill gripping Harry Dresden's finances, his wizardly business having hit a dry spell. Just as the hunger pangs begin to truly set in, a call comes that promises to stir things up. Lieutenant Karrin Murphy of Special Investigations, her relationship with Harry still strained from their last supernatural entanglement, needs his unique expertise. A brutally savaged body, a henchman of the city's crime lord Johnny Marcone, has been discovered, surrounded by wolf-like paw prints, and the full moon looms. Harry, with a wizard's sight, immediately recognizes the signature of something far more sinister than any ordinary animal attack.
The investigation is immediately complicated by the arrival of a team of FBI agents, led by Agent Denton, who are clearly more than they seem. Harry, ever the pragmatist, manages to snag a shard of bloody glass from the crime scene, using it to magically track a lead. This trail pulls him into the shadowed world of Tera West, a mysterious woman who leads a gang of young, college-aged werewolves known as the Alphas. It is from her that Harry learns of a far more ancient and terrifying breed of creature: the loup-garou, a monstrous, cursed werewolf, and its connection to her fiancé, Harley MacFinn, a wealthy environmentalist. MacFinn is a man trapped by a hereditary curse, transforming into an unstoppable killer under the pale light of the full moon.
As the moon waxes, the body count rises, and the city tightens its grip in fear. Murphy, desperate and under immense pressure, arrests MacFinn in his human form, ignoring Harry's urgent warnings about the true nature of his curse. The consequences are swift and horrific. Imprisoned at the police station, MacFinn transforms, unleashing a bloody rampage that devastates Murphy's staff and the holding cells. Harry, wounded and on the run, is rescued by Tera, who desperately seeks his help to reconstruct the powerful magical circles that might contain her monstrous fiancé.
The web of supernatural intrigue grows denser. Harry discovers that the FBI agents are not merely investigators but hexenwolves, using enchanted belts to transform into their bestial forms. Their true, insidious plot begins to unravel: to frame MacFinn for the murders and eliminate Marcone, who has his own interests in the land MacFinn seeks to protect. Harry finds himself caught between warring factions of supernatural predators, struggling to protect the innocent, navigate his crumbling relationship with Murphy, and untangle the layers of deception.
The climax erupts in a furious confrontation on Marcone's estate. Harry, alongside Tera and the Alphas, faces off against Denton and his hexenwolf team, a brutal clash of magic, claws, and gunfire. In a desperate gambit, Harry even dons a stolen hexenwolf belt, briefly embracing the monstrous power to turn the tide. Amidst the chaos, he uses a powerful pentagram, a gift from his mother, to finally subdue the rampaging loup-garou. The events leave a profound mark, revealing the dangers of unchecked power and the blurred lines between good and evil in Chicago's hidden depths.
