Harry Potter and the Dealthy Hallows is the seventh and final book in J.K. Rowlings Harry Potter series. Voldemort is continuing to accumulate power and it is up to Harry, Ron, and Hermoine to find the remaining Horcruxes to defeat him once and for all. When the Death Eaters descend upon Hogwarts, it leads to a battle that will affect the future of the wizarding world forever.
Hermione has fortunately packed them sleeping bags and when Harry wakes up the next morning he sees that Ron and Hermione fell asleep holding hands. The sight of them makes him feel a little bit lonely.
While they’re still sleeping, Harry creeps upstairs to Sirius’s room and goes inside. He’s amazed to find a letter to Sirius from his mother, Lily. It describes the baby Harry and his love for the broomstick Sirius gave him for his first birthday, also how Dumbledore still has James' Cloak, but part ofthe letter is missing and the text ends just as Lily's going to write something shocking about Dumbledore, and so Harry searches frantically around the room for the rest of the letter, but he couldn't find it anywhere.
On the way back downstairs Harry finds a sign on another door from Sirius’s brother, Regulus Black. His initials are R.A.B, the same ones that were on the fake locket Horcrux that Harry and Dumbledore retrieved last year. The three search the room for over an hour looking for the real locket but don’t find it. Hermione, however, remembers they threw away a locket last summer when they were cleaning out the house. Harry is horrified, because he now realizes that the locket is Voldemort’s true Horcrux.
Harry summons Kreacher to ask him if he stole the locket back and the elf tells him that he did. He tells Harry that Mundungus Fletcher stole it from him, and now Kreacher doesn’t know where it is.
Kreacher then tells Harry an amazing story of how he came to know where the original locket was, and how Regulus gave his own life to try and destroy the Horcrux with Kreacher’s help. Harry then asks Kreacher very nicely if he would go find Mundungus so they could continue Regulus’s work and ensure he didn’t die in vain.