Ever since his girlfriend left town to deal with her newly acquired taste for blood, Harry Dresden has been down and out in Chicago. He can't pay his rent. He's alienating his friends. He can't even recall the last time he took a shower.
The only professional wizard in the phone book has become a desperate man.
And just when it seems things can't get any worse, in saunters the Winter Queen of Faerie. She has an offer Harry can't refuse if he wants to free himself of the supernatural hold his faerie godmother has over him — and hopefully end his run of bad luck. All he has to do is find out who murdered the Summer Queen's right-hand man, the Summer Knight, and clear the Winter Queen's name.
It seems simple enough, but Harry knows better than to get caught in the middle of faerie politics. Until he finds out that the fate of the entire world rests on his solving this case.
No pressure or anything...
The Red Court of Vampires declares war on the White Council. It's two years after the events in Storm Front. Harry Dresden, struggling with finding a cure for Susan Rodriguez's vampiric infection, is approached by Mab, the Winter Queen. Mab purchased Dresden’s debt from his fairy godmother, the Leanansidhe. Queen Mab tells Dresden he can pay off his debt by doing three favors. The first favor is for him to find the murderer of the Summer Knight, Ronald Reuel, and recover his stolen mantle, declaring Dresden her chosen Emissary. Dresden refuses her request, but is forced by the White Council to accept as his Trial, else be stripped of his title of wizard and handed over to the Red Court vampires as a peace offering.
At his home, Dresden finds Elaine Mallory, his former fellow apprentice and lover, who is the Emissary of the Summer Court and heavily indebted to Aurora, the Summer Lady. Dresden goes to Reuel's funeral, looking for a group of teenage half-human/half-Fae changelings who were Reuel's friends, but they flee and attack, believing him to be in service to Winter. Dresden gets information and a guide to the Winter and Summer Ladies. Dresden’s interview with the sadistic Winter Lady, Maeve, convinces him that she did not kill the Summer Knight.
Approached by the changelings to find their friend Lily, after Dresden tells Meryl and Fix that he will look for Lily. Dresden discovers Elaine in the back seat of his car, dying of multiple stab wounds. He follows Elaine’s delirious advice to take her to the Summer Lady, Aurora. Aurora heals Elaine, and briefly comforts Dresden. She is not forthcoming with any details on Reuel’s murder or Lily’s disappearance. Instead, she explains that the death of the Summer Knight and the theft of his mantle of power shifted the power balance in favor of Winter. Summer must now attack Winter at Midsummer to maintain control over their remaining power.
Dresden heads north to an isolated spot on Lake Michigan and summons his fairy godmother, the Leanansidhe. Dresden tells his godmother that he needs to see the Faerie Queens and Mothers. the Leanansidhe instead takes him transported to an ethereal Chicago-over-Chicago and a great Stone Table. This sacrificial stone that maintains the balance between the Winter and Summer Sidhe. The power of blood spilled upon that table will change the balance of power between the Courts. The Leanansidhe says she can do no more for him and disappears.
Dresden still needs to speak with the Mothers of both Courts. He tracks Elaine to O'Hare International Airport and persuades her to call in some favors so he can get an invitation to see the Mothers. Rather than provide him with answers, they goad him into answering his own questions, that Aurora is the only Queen capable of stealing the Summer Knight's mantle, and therefore one of his killers. Lily captured the mantle, being the closest Summer fae at the time of his death, and was turned to stone by Aurora, which is why no one could find either Lily or the mantle. As a reward for his correct deductions, they give him a Cloth of Unraveling and their blessings.
Victorious at last, Dresden returns to Elaine and is ambushed. When Dresden regains consciousness, he is the prisoner of Aurora, the Winter Knight Lloyd Slate—and Elaine, who has been coerced into helping with the plot. Aurora explains that she plans to sacrifice Lily on the Table to give Winter the power of the Summer Knight, permanently destroying the balance and freeing humanity from the constant collateral damage of the eternal Faerie War. Elaine then binds Dresden and leaves him to drown. Recognizing the spell he and Elaine invented, Dresden easily escapes. Collecting his friends, they fight their way to the Stone Table and the Winter Queen, telling her of Aurora's plan. Dresden confronts Aurora and unleashes an army of pixies armed with steel-bladed box cutters--cold iron, which is deadly to the Fae.
After the pixies kill Aurora, Queen Mab congratulates Dresden on his success, and offers Dresden the mantle of the Winter Knight, which he refuses. Queen Mab grants safe passage to the White Council. Having passed his Trial, he retains his wizard accolades, and protection from the Red Court. The new Summer Lady, Lily, and her new Summer Knight, Fix, pay Dresden a visit and grant him a favor of Summer in thanks for his services.