Harry Dresden, Chicago's only professional wizard, is about to have a very bad day...
Because as Winter Knight to the Queen of Air and Darkness, Harry never knows what the scheming Mab might want him to do. Usually, it’s something awful.
He doesn’t know the half of it...
Mab has just traded Harry’s skills to pay off one of her debts. And now he must help a group of supernatural villains—led by one of Harry’s most dreaded and despised enemies, Nicodemus Archleone—to break into the highest-security vault in town, so that they can then access the highest-security vault in the Nevernever.
It's a smash and grab job to recover the literal Holy Grail from the vaults of the greatest treasure hoard in the supernatural world—which belongs to the one and only Hades, Lord of the freaking Underworld and generally unpleasant character. Worse, Dresden suspects that there is another game afoot that no one is talking about. And he's dead certain that Nicodemus has no intention of allowing any of his crew to survive the experience. Especially Harry.
Dresden's always been tricky, but he's going to have to up his backstabbing game to survive this mess—assuming his own allies don’t end up killing him before his enemies get the chance...
The novel opens with Harry Dresden still living on the island of Demonreach. He is approached by the spirit of the island, informing him that Queen Mab has arrived. Dresden meets her at the docks, where she tells him that she has a job for him to do. They make their way to the Hard Rock Hotel[Footnote 1] where they meet with Nicodemus Archleone. Dresden learns that the job Mab has in mind for him is to help Nicodemus steal something from the vault of Hades. He argues with Mab over this, but she convinces him to do it by pointing out that once the job is done, he will be permitted to take a shot at Nicodemus. Wary of the potential for betrayal, he enlists the aid of Karrin Murphy to watch his back.
The next morning, Dresden and Murphy arrive at an old meat packing plant; the location of their first meeting with Nicodemus. They observe Binder and a female warlock, Hannah Ascher, arriving at the meeting place. Over the next two days, Dresden is given a series of jobs by Nicodemus. First, he must recruit Anna Valmont, the only surviving member of the group of thieves who had stolen the Shroud of Turin in Death Masks. The second is to accompany Deirdre Archleone and the shape-shifting new addition to the group, Goodman Grey, as they collect a 'sample' from a high-end financial worker. Dresden tries to keep the man alive, but ultimately fails when they are attacked by Polonius Lartessa. In addition to this, Dresden learns that they are after the Holy Grail.
At the third meeting, they realize that they are being spied upon by Waldo Butters. Giving chase, Dresden manages to keep Binder's henchmen from catching him with the help of Bob. Nicodemus catches up with Dresden, Murphy and Butters on the street in front of Michael Carpenter's house, and a fight ensues. Murphy draws Fidelacchius and seems to be getting the better of Nicodemus, until she is tricked into using the sword to attempt to kill him while defenseless, in violation of the nature of the sword, which results in the sword shattering. Michael then appears, offering to leave his house (which is protected by angels) in exchange for the release of Dresden, Murphy and Butters. Nicodemus accepts the deal, but before Michael leaves, Uriel appears, giving him Amoracchius and his own power as an angel. Nicodemus relents and agrees to accept Michael as Dresden's replacement for the wounded Murphy.
The new group then set out to pull off the heist. First, they must break into a real world high security vault, in a bank owned by John Marcone and located in the Capristi Building. Ascher gets them inside the building, while Binder keeps Marcone's men busy outside. Once at the vault, Valmont cracks open the door, and they enter. Despite another attack by Tessa, they make their way into an inner vault owned by Hades, where Dresden opens a Way to the true vault, in the Nevernever. Once there, Nicodemus sacrifices Deirdre Archleone to gain entrance to the vault, where Dresden has a private conversation (unbeknownst to the others) with Hades himself. Once the grail is in his hands, Nicodemus wastes no time in turning on Dresden and Michael. Hanna Ascher and Genoskwa, an aggressive Bigfoot-like entity, are the new hosts for Lasciel and Ursiel, respectively. Nicodemus orders them and Goodman Grey (who had supposedly killed Valmont) to attack. At this point, Dresden remembers his first stop with Mab after their meeting with Nicodemus, where he had hired Grey to back him up prior to the planning of this mission. Grey turns on Genoskwa/Ursiel, while Dresden kills Ascher/Lasciel and Michael chases off Nicodemus. They then gather up the still-living Valmont and make their escape from the nevernever, but not before Nicodemus escapes and heads for Michael's house. With Binder's help, they get out of Marcone's vault and confront Nicodemus at Michael's home. During the final fight, Butters takes up the broken Fidelacchius, which emits a lightsaber-style blade and chases off Nicodemus again.
Afterwards, the group divide up a backpack full of diamonds Valmont had stolen from Hades' vault. Dresden pays Grey's fee of 1 dollar in cash, and uses Grey's unwanted share of the diamonds to bribe Marcone into forgetting the break-in, then visits Murphy in the hospital where the two share a passionate kiss. Talking with Michael that evening, they reflect over the events of the past few days, leading them to worry about Dresden's future as the Winter Knight.
Dresden figures out that everyone in the heist was a pawn. The plot was hatched between Mab and Marcone, to avenge themselves on Nicodemus, with the help of Hades. The plot succeeds: Nicodemus loses Deirdre Archleone and all his acolytes and his underworld reputation, but of course gains the Holy Grail as Mab had promised.