Harry Dresden teams up with old flame Susan Rodriguez to save their daughter Maggie from the vampires of the Red Court. Wizard Harry Dresden didn't know about his daughter, Maggie, until a phone call from his ex informs him that she's been kidnapped by Red Court agents. Harry soon reunites with Susan Rodriguez, his half-vampire ex, and her partner Martin, both of whom have been working with the Fellowship of St. Giles to disrupt the operations of the Red Court. They soon bring in allies, including Harry's apprentice Molly, Harry's longtime friend and ally Karrin Murphy, and Harry's half-brother Thomas Raith of the White Court, to help them find and rescue Maggie.
Red Court agents aren't the only threats in Harry's way. Following the explosive destruction of Harry's office building by the Red Court, Harry finds himself under suspicion by the FBI, forcing him to collect his most valuable, dangerous, or illegal belongings and hide them in the Nevernever before the cops arrive. Later, his apartment building is burned down in another attempt on Harry's life, and his back is broken in a fall. Although Sanya, a Knight of the Cross, is able to help Harry get to safety, neither Sanya nor Harry's other allies can restore his back in time to make any difference.
He speaks to Mab, Queen of Air and Darkness, and takes up the mantle of the Winter Knight, and kills the previous Knight at Mab's behest. As part of his agreeing to serve as the Winter Knight, Harry exacts a promise of aid from the Winter Queen, and he is sent to help Harry and his allies to recover Harry's daughter.
Using information Harry's mother left him regarding the various Ways of the Nevernever, Harry and his allies set out toward Chichen Itza, the site of a massive Red Court ritual that will set off a bloodline curse, killing Maggie, Harry, Harry's brother Thomas, and any other relatives (such as Harry's grandparents and THEIR siblings, though Harry doesn't know who his grandparents are).
There is a massive battle at Chichen Itza. A large portion of Harry's allies take part, including the Grey Council, and eventually some hundreds of kenku (who owed Ebenezer McCoy a favor, and so arrived after he and the rest of the Grey Council appeared). Eventually, Harry, Susan, and Martin reach the top of the pyramid upon which the death curse has been readied, and Martin betrays them, causing Susan to attack and kill him. This turns Susan from a half-Red into a full Red Court vampire--and she and Harry realize that, as the youngest Red Court vampire, Susan can be killed to set off the bloodline curse on the Red Court instead of Harry's family.
Harry kills Susan, saving his daughter and destroying the Red Court utterly. Upon Harry's return to Chicago, Maggie is placed in a safe home, and Harry returns to the Water Beetle to sleep and get cleaned up. He and Murphy agree to meet up, to see what might develop, but when Harry walks outside to await her arrival, a distant shooter attacks him, and Harry is mortally wounded. He falls into Lake Michigan and sees a very bright light, accompanied by the sound of an oncoming train.
Best part of story, including ending:
It brought in a ton of important characters, including some we haven't seen much of yet, such as Vadderung. It changed Harry's life in major ways, bringing in a daughter but destroying most of Harry's mundane possessions. It showed Mouse in full battle form, willing to face off against one of the most terrifying Sidhe of the Winter Court. It had bits of Harry's trademark humor, but was also very serious when that was more appropriate. And in general, it was fantastically well-written.
Best scene in story:
There are several excellent ones. When the Leanansidhe decides to redo Harry's and Susan's clothing, in order to make it more appropriate to the occasion as well as more well-armored, there's a pretty hilarious bit where Harry is discomfited and has no way to get out of it; it's like magical clothes-shopping with an Unseelie psychopath. (This is followed shortly thereafter by Harry's allies deciding that if this were the LotR, the Leanansidhe would clearly be Gandalf, since she's so good with magic even if she is extremely murderous at times.)
Opinion about the main character:
Harry is brave, self-sacrificing, funny, and incredibly determined. He knows when to ask for help, but is also a formidable power in his own right.