"For Harry Dresden, Chicago's only professional wizard, there have been worse assignments than going undercover on the set of an adult film. Dodging flaming monkey poo, for instance. Or going toe-to-leaf with a walking plant monster. Still, there's something more troubling than usual about his newest case. The film's producer believes he's the target of a sinister entropy curse, but it's the women around him who are dying, in increasingly spectacular ways.
Harry's doubly frustrated because he got involved with this bizarre mystery only as a favor to Thomas, his flirtatious, self-absorbed vampire acquaintance of dubious integrity. Thomas has a personal stake in the case Harry can't quite figure out, until his investigation leads him straight to Thomas's oversexed vampire family. Harry's about to discover that Thomas's family tree has been hiding a shocking secret: a revelation that will change Harry's life forever."
Harry Dresden and Thomas Raith, after meeting for dinner, rescue a litter of pups from a group of demon gorillas, and deliver them to Brother Wang's, their owner, just as he is leaving. On the ride home Dresden finds another pup hiding in the car, who alerts Dresden to a vampire attack. Thomas introduces Dresden to a friend, Arturo Genosa, who produces movies. Arturo hires Dresden to investigate the suspicious deaths of two women. Dresden will pose as a production assistant to investigate and apprehend the murderer along with Thomas.
Deciding that the Black Court vampires need to be killed as quickly as possible, Dresden enlists Karrin Murphy and later calls on Ebenezar McCoy to be a wheelman and counter Mavra's magic. The next day, Dresden shows up early at the film studio. When the next curse hits the studio, Dresden is able to intervene and save the lives of two of the stars, though they are badly hurt and electrically scarred. Dresden realizes that Arturo is not the target of the curses, but the women in his life. Later while collecting information, someone tries to murder Dresden with a blowgun dart.
One of the replacement actresses is the attractive Lara Romany (Lara Raith, a White Court vampire), along with her sister Inari and brother Thomas. Seeing a form flee the studio, Dresden gives chase and tackles Thomas. Thinking Thomas is using Dresden as a catspaw, Dresden beats Thomas badly, and is ambushed by Lara. She shoots Thomas. Before she can shoot Dresden, they are jumped by Mavra's minions. They escape, but Thomas is dying, as he used up his energy reserves in the fight. Inari's arm is shattered. Lara and Dresden evacuate them to the Raith's mansion for medical attention. Lara offers Dresden the hospitality and protection of her home. Lord Raith, her father and the King of the White Court vampires, is not bound by her word. Later, Raith sends a drugged Inari to feed on Dresden, but she is burned by touching him.
Thomas arrives just in time to hustle Inari away, and explains that Dresden is still protected by Susan's love. In Lord Raith's gallery, he shows Dresden the painting of their mother, Margaret Gwendolyn LeFay. Thomas is Dresden's half-brother, which Dresden does not believe. Still disbelieving, Dresden soulgazes Thomas. During the soulgaze, they both receive a planted message from their mother: help each other. Dresden agrees to help Thomas save Inari from Lord Raith, as if Inari falls in love before shes feeds, the vampire curse will fail.
The next morning, Dresden meets Kincaid and Lt. Murphy to coordinate the raid on Mavra, before hurrying back to the studio to prevent the next curse. He drafts Jake into helping draw a magical lightning rod. Jake mentions that Arturo is getting married for the fourth time. Dresden confirms with Murphy that Arturo has a marriage license for Thursday. The fax is blurred, so she cannot read the name of the bride-to-be. Unlike the prior three wives, this Mrs. Genosa was not required to sign a pre-nuptial agreement. If Arturo dies, she will inherit everything, which is the motive. Trixie then surprises him at gunpoint, so he cannot interfere with the curse, and Trixie has destroyed his spell shield. Trixie and her co-conspirators have no idea who Arturo is marrying, so they are killing all the women around him. The next curse will kill Emma. Desperate to save her, Dresden jumps Trixie. She fires wildly, killing Emma.
Trixie screams that Dresden killed Emma. The entire cast and crew see him holding the gun. Dresden flees, handing the gun off to Joan as he runs out the door, giving her a brief synopsis of what Trixie has done. Back at his apartment, Bob gives Dresden the location and a site map of the vampire hideout in a homeless shelter. They pick up Murphy from her family picnic and rendezvous with Kincaid. Kincaid and Ebenezar know each other from before, and share mutual hatred. They give their word to Dresden for a temporary truce, so they can shut down Mavra and her scourge. Impersonating Red Cross workers, Kincaid and Murphy evacuate the homeless people and shelter staff from the ground floor. Ebenezar keeps the truck running, while they go into the basement lair, finding an imprisoned group of children. Mavra and her henchmen ambush them with flamethrowers, setting the building on fire. Dresden's shield protects them, but it absorbs the heat energy, incinerating his left hand. Dresden sends the flame back at the vampires, and he and Kincaid manage to overpower them. Gathering the children, they flee the burning building.
Kincaid leaves, giving Dresden three days to pay him or die. Murphy and Dresden take the rescued children to Fr. Forthill. Ebenezar explains that a Blackstaff is the White Council's assassin, allowed to break the Laws of Magic as he sees fit to protect the Council. Also, he tells Dresden that his mother, Margaret LeFay, was his apprentice. And finally, Margaret was murdered by Lord Raith, but that Raith is spectacularly protected from magic, and even Margaret's death curse didn't seem to do anything. Dresden coopts Lara to overthrow Raith, finding Mag and Trixie with him in the Deeps, planning to sacrifice Thomas to kill Dresden with the curse, freeing Lord Raith from Margaret's death curse, which has prevented Raith from feeding for years, leaving him extraordinarily weak. Mag kills Trixie with a spell, then summons He Who Walks Behind to kill Dresden, but the spell is interrupted, and the Outsider kills Mag, fleeing into the night. Lara arrives, and mentally overpowers Raith. She makes her father into a puppet, so their enemies won't see any weakness in House Raith or the White Court. Banished from House Raith, Thomas moves into Dresden's apartment, and pays off the mercenary Kincaid as thanks for saving his life.