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
The Magical Worlds of Harry Potter approval from Rowling, and has since received positive reviews from critics. An updated version of "The Magical Worlds of Harry Potter" was published in 2004 by Berkley Books. "The Magical Worlds of Harry Potter" explores the references to history, legends, and literature in J.K. Rowling's "Harry Potter" novels. David Colbert, the author of the book, told the "St. Louis Post-Dispatch" that the "Harry Potter" novels "are [...] literary treasure hunts for [Rowling's] readers. What seem like funny-sounding names and places and excursions into fantasy all have a basis in either history, myth or legend." He added, however, that he thinks