Chapter 11 - "The Firebolt" - In which Harry mulls over what he heard about Black, almost everyone has gone on holiday, HRH go to visit Hagrid, find him distraught about Buckbeak's hearing before the Committee for the Disposal of Dangerous Creatures, and HRH begin seeking precedents to help Buckbeak's case. Christmas comes and Harry gets a Firebolt broom from an unknown (Black) benefactor, Crookshanks goes after Scabbers again and revives bad feelings between Ron and Hermione, dinner is taken with the teachers, and McGonagall confiscates the Firebolt to check for jinxes.

A Gift From Fred and George
As his classmates head off to [Hogsmeade] the day before the holiday, Harry settles in to read a magazine when Fred and George pull him aside and hand him the Marauder's Map, showing secret passages out of the castle, and Harry sets off to take a secret passage to [Hogsmeade].
Harry uses the Marauder's Map to get into the secret passage to [Honeydukes], finally squeezing through a crowd to find Ron and Hermione amidst the candy shelves.
Eavesdropping in the Three Broomsticks
After some convincing, Hermione finally relents and agrees to lay off of Harry for breaking the rules - especially when Ron points out that there's no way Sirius Black could possibly be around - and the three of them head off to see the rest of [Hogsmeade].
After walking through [Hogsmeade] for a bit, Harry, Ron, and Hermione decide to visit the [Three Broomsticks] for a [butterbeer], which Harry instantly loves.
Harry's joy is interrupted when the door to the [Three Broomsticks] opens and a group of teachers, along with Cornelius Fudge, walk in. Hermione and Ron hide him under the table and together they listen in to the conversation, learning that Sirius Black was best friends with James Potter, and that he betrayed James and Lily to Voldemort.
Harry manages somehow to get back to Hogwarts and make it through dinner, then running up to his [dormitory] and faking sleep, all the while thinking about how Sirius Black betrayed his parents.
Buckbeak is Condemned
Harry wakes up to find the common room deserted except for Ron and Hermione, and the three of them talk about Harry's reaction to learning that Sirius Black betrayed his parents. Finally, after a charged conversation, Ron convinces Harry to visit Hagrid.
Upon arriving at Hagrid's, Harry, Ron, and Hermione discover him sobbing over the fact that Buckbeak has been sentenced to death. The kids comfort him and vow to help with the appeal before departing.
Harry, Ron, and Hermione return to the library to look for ways to help Buckbeak's appeal.