Chapter 3 - "The Knight Bus" - In which Harry tries to decide what to do, the Knight Bus arrives, and he asks to be taken to London. En route Harry learns about Sirius Black. He is met by Cornelius Fudge at Diagon Alley and installed in a room at the Leaky Cauldron.
The Trip to the Leaky Cauldron
Harry collapses in Magnolia Crescent, certain that he's been expelled from Hogwarts for blowing up [Aunt Marge]. He begins plotting an escape and a life on the run when he feels, then sees, a large animal, and while backing away falls over.
The [Knight Bus] unexpectedly arrives with a bang, and Harry has to roll over to avoid being crushed. [Stan Shunpike] welcomes Harry aboard, and he quickly claims to be Neville Longbottom and pays his fare, as the bus takes off again.
Harry wonders about his punishment for blowing up [Aunt Marge], as the other passengers disembark the [Knight Bus] one by one. Finally, the bus arrives at the [Leaky Cauldron], and Harry gets off himself.
No sooner does Harry disembark from the [Knight Bus] than he runs into Cornelius Fudge, the [Minister for Magic]. [Stan] and [Ernie] gawk at him once they learn his real identity, and Fudge takes Harry to a private room in the [Leaky Cauldron].
Harry Arrives at the Leaky Cauldron with a Bang
Cornelius Fudge kindly informs Harry that [Aunt Marge] has been put back to normal, and the [Dursleys] are willing to welcome him back, but Harry is confused that he isn't being punished for such a severe breach of wizarding law. Fudge then arranges for Harry to stay at the [Leaky Cauldron], elects not to sign his [Hogsmeade] form, and departs.
Chapter 4 - "The Leaky Cauldron" - In which Harry enjoys his new-found freedom, purchases his school supplies, and meets with Hermione and Ron. Hermione buys Crookshanks after the cat takes after Ron's Scabbers. Back at the [Leaky Cauldron], Harry overhears Mr and Mrs Weasley talking about the danger he is in.
Glorious Days in Diagon Alley
Harry spends his days wandering [Diagon Alley], taking in the sights at the [Leaky Cauldron], hearing shoppers discuss Sirius Black, getting homework help from Florean Fortescue, eyeing the [Firebolt] in the window of [Quality Quidditch Supplies], and stocking up on supplies for the school year.