Hermione Granger is crucial to Harry and Ron in their successful mission to solve the mystery of the Chamber of Secrets. Hermione is revived after Harry kills the basilisk, but she is distraught to learn that all end-of-year exams have been cancelled as a school treat. Hermione buys a cat named Crookshanks, who takes to chasing Ron's pet rat, Scabbers. Before the start of term, Professor McGonagall secretly gives Hermione a Time-Turner, a device which enables her to go back in time and handle her heavy class schedule, though this is not revealed until the penultimate chapter. Much tension comes into play
Harry Potter and the Half-Blood Prince continue. Harry finds out that the locket is not the real Horcrux, containing only a note from someone named "R. A. B.". Harry is so devastated by Dumbledore's death (and upset by its futility) that he tells his friends he will not be returning to Hogwarts. Instead, he will spend the next year searching out Voldemort's Horcruxes. Ron and Hermione insist on joining him in destroying Lord Voldemort for good. "Harry Potter and the Half-Blood Prince" is the sixth book in the Harry Potter series. The first book in the series, "Harry Potter and the Philosopher's Stone", was first published