Chapter 6 - "Draco's Detour" - In which we learn of several disappearances including Florean Fortescue and Mr. Ollivander, and Harry, Hermione, and the Weasleys go shopping at Diagon Alley, escorted by Hagrid. There they discover a much-changed atmosphere and an empty Leaky Cauldron, have a run-in with Draco and Narcissa Malfoy in Madam Malkin's, tour Weasleys' Wizard Wheezes, and sneak out to follow Draco into Borgin and Burke's, where they overhear a mysterious conversation between him and Mr. Borgin.
In Fred and George's Room
Tidings of Mysterious Disappearances and Deaths
Harry spends several weeks at the [Burrow], playing [Quidditch] and hearing about frequent disappearances and deaths.
A Very Different Diagon Alley