The book open with Harry briefly visiting the Dursleys one last time, per Dumbledore’s instructions, with Ron and Hermione going along for protection. Death Eaters attack on his 17th birthday and it seems our heroes are in serious trouble—until Petunia inadvertently does magic to save her Duddykins. That’s right—Petunia is a witch, but gave up all that nonsense to live a normal life as a Dursley. However, they are now all in serious danger, and the Dursleys are whisked away to Grimmauld Place. Comic relief ensues.
Bill and Fleur’s wedding is a tense and secretive affair, due to the general state of things. Harry comes to realize (with the prompting of friends) that loving Ginny means he has to let her take risks for him if she wants to. They get back together and the trio becomes a quartet.
The kids return to school intending to complete their training in relative safety, only to discover Hogwarts in major chaos. Many of their classmates simply have not returned and the teachers are weak without Dumbledore. Hogwarts is no haven anymore, and thus Harry Has Become A Man. He has a conversation with Portrait-Dumbledore, who gives him Very Good Advice. Harry decides to leave school, and his friends follow (much to Hermione’s anguish).
In secret, Snape comes to Hermione alone and tells her a crazy tale of his killing Dumbledore on Dumbledore’s own orders (either to release Draco from his mission, to release Snape from his Unbreakable Vow, or to save Dumbledore from a fate worse than death—or possibly all three). Why Hermione? Because Hermione is the only one who wouldn’t try to kill Snape on sight. She thus has a big decision to make: trust Snape or no? Because we wouldn’t have a story otherwise, she does.
Hermione also deduces from their conversation that Snape has been a double agent for Dumbledore as far back as before the prophecy was made. Snape refuses to confirm or deny.
Snape begins passing information to Harry through Hermione and because of him, they destroy one or two horcruxes. From Harry’s point of view, Hermione seems to be a spectacular horcrux hunter, making fantastic logical leaps on scant information. Finally, Harry gets suspicious of how good she is and confronts her. She admits tearfully that she’s in contact with Snape and he’s the one really responsible for their success so far. Big confrontation in which Harry remains furious with Hermione, yet decides to trust Snape—but only a little.
But where has Malfoy been this entire time? He fled from Snape the night Dumbledore was killed (and Snape suffered mightily for allowing his escape), and he now thinks Snape is a True Believer. Draco, on the run and forced to think for himself for the first time in his life, has come to realize something very strange about the way Voldemort is behaving: The Dark Lord is not acting like someone who wants to take over the world. He’s acting like someone who wants everyone dead but himself—not so good for the Malfoys. Draco comes to Harry with his ideas, haughtily demanding the right to join their side and exact revenge for his father.
Harry, thinking back on the memories in the pensieve, pieces together the final truth: when poor and orphaned Tom Riddle was sorted into Slytherin, he was treated badly by the good eggs because of his actions and general creepiness and treated badly by the bad eggs for his bloodline and lack of social clout. The other houses are prejudiced against Slytherins from the start. With no real future waiting for him, he decides to avenge himself on the entire wizarding world by building a vicious pureblood movement and using that as wedge and hammer to destroy the entire wizarding community. Thus the only way to defeat Voldemort is by uniting all of wizardom against him.
When the quartet plus Malfoy get down to the last horcrux, they discover to their surprise (but no one else’s) that Harry scar is the final horcrux. After the final confrontation in which representatives of all four houses band together to defeat Voldemort, (possibly by pushing him through the veil in the Ministry), the final horcrux still remains. Knowing time is short, Harry attempts to throw himself through the veil to finish Voldemort off, but Snape swoops in, saying there’s a better way. Snape disarms the final horcrux and saves Harry’s life at the cost of his own.
Harry is thus left victorious…but why doesn’t his wand work? Alas, he has destroyed his magical power along with the horcrux. He remains grateful for life and love, but returns to the Muggle world and lives as a recluse. Hermione, Ron, the DA, and the others struggle to slowly rebuild their world, sadder but wiser.
Coda: When Snape’s will is read and final letters to the living dispursed, we discover that the reason Dumbledore trusted Snape was because Dumbledore insisted as a condition of Snape’s service that Snape make an Unbreakable Vow to Lily Potter to protect and watch over her son no matter what. Harry’s greatest tormentor was thus also his greatest ally all along.
Not that I’ve given this much thought… :dubious:
