In a nearby park, Harry is almost attacked by a mangy black dog. He's saved in the knick of time by the Knight Bus…which is (k)not what it seems. It's a magic bus, zipping through the streets invisible to the eyes of Muggles. It deposits Harry at the Leaky Cauldron, where the Minister of Magic forgives Harry for inflating Marge like a pigeon at a wedding.
At the Cauldron, Harry's reunited with his buds Ron and Hermione. Ron's father informs Harry that Sirius Black, who just escaped from Azkaban, wants to kill Harry, and that Harry needs to be safe:
HARRY: Mr. Weasley, why would I go looking for someone who wants to kill me?
(If Mr. Weasley believes this line, he clearly hasn't seen the other two movies.)