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].
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].
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.
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.